TICAL 




OOLOG 




COLTON 



LIBRARY OF CONGRESS. 



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UNITED STATES OF AMEEICA/ rt „ mT „ TrT , n 

-^CONTENTS. 



Introduction Paoes v-xvi 



PAGE 

Grasshopper ..... 1 

Cricket 9 

Bumble Bee 10 

Butterfly 11 

House Fly 15 

Squash-bug 17 

Beetle 17 

Dragon-fly 19 

Spider 21 

Thousand Legs .... 22 

Crayfish 24 

Sow-bug 36 

Cyclops 37 

Earthworm 40 

Fresh-water Clam ... 46 

Snail 56 



PAGE 

58 



60 
62 
69 
70 
86 
98 
102 



Paramecium .... 
Bell- animalcule . . 

Amceba 

Wheel-animalcule 

Fish 

Frog 

Snake . . . . ... . 

Turtle 

Pigeon . 105 

Rabbit 119 

Starfish 150 

Sea-urchin 160 

Fresh-water Hydra . . 166 
Sea-anemone . . . . . 171 

Coral Polyps 172 

Sponges . . . . . . . 176 



Books of Reference 181 



,V 3 1886 



AN 



ELEMENTARY COURSE 



Practical Zoology. 



BY 

BUEL P. COLTON, 

Instructor in Natural Sciences, Ottawa High School, Illinois. 




BOSTON: 

D. C. HEATH & COMPANY. 

1886. 



Copyright, February 20, 18P6, 
By BUEL P. COLTON., 



QL53 



J. S. Gushing & Co., Printers, B 



PREFACE. 



In the entire absence of any handbook of zoology 
adapted to the grade of work in which he was engaged, 
the author began to draw up, for use in his own classes, 
simple guides to the study of a few common animals. 
After repeated tests in the class-room, and under the 
advice of a number of eminent teachers of the subject, it 
was decided to put the work into print. 

The author takes this opportunity to thank those who 
have so heartily aided him in this undertaking. 

Prof. Alpheus Hyatt, of the Boston Society of Natural 
History, has generously aided in preparing the book for 
publication. 

Pres. D. S. Jordan, of Indiana University, has read 
most of the manuscript and proof-sheets, and has given 
many valuable suggestions. 

Especial thanks are due also to H. Garman, Assistant- 
Professor of Zoology, University of Illinois, for corrections 
and suggestions on the entire manuscript and on the proofs. 

Mr. B. H. Van Vleck, Assistant, Boston Society of 
Natural History, revised the manuscript on Echinoderms, 
Coelenterates, and Sponges. 

As the proof-sheets appeared, from time to time, 
they were critically read by Prof. N. S. Shaler, Harvard 



iv PREFACE. 

University ; Mr. J. Y. Bergen, Jr., Peabody, Mass. ; Prof. 
R. E. Call, Missouri Agricultural College and University, 
Columbia, Mo. ; Mr. E. P. Jackson, Boston Latin School ; 
Prof. L. M. Underwood, Syracuse University, Syracuse, 
N.Y., and other well-known teachers. In the preparation 
of the book, free use has been made of the works cited in 
the text. 

To aid in the study of the marine animals, arrangement 
has been made by which schools may be supplied with 
sets of material put up at the Seaside Laboratory, Annis- 
quam, Mass. A list of these specimens will be found at 
the end of this book. They may be obtained of Mr. B. H. 
Van Vleck, Assistant, Boston Society of Natural History. 

It is believed that with the assistance above acknowl- 
edged, the book will be found fairly free from errors ; but, 
for any mistakes it may contain, the author alone should 
be held responsible. 

The author believes that he has encouraged only the 
most merciful methods of handling live animals, and he 
would strongly urge all teachers not to do anything that 
might lead to cruelty to animals. 

The only way to know animals, is to see and to handle 
them ; and it is sincerely hoped that the day is near when 
knowing an animal's name will not pass for knowing the 
animal itself. If this little book should do somewhat 
toward the improvement of methods of teaching zoology, 
the author will feel that he has not labored in vain. 

• Ottawa, III., Aug. 20, 1886. 



INTRODUCTION. 



This work is designed to aid the student in getting a 
clear idea of the animal kingdom, as a whole, by the care- 
ful study of a few typical animals. 

Most of the animals selected are abundant in the interior 
States, and are easily collected. 

These guides to the study of animals have been used 
several years, and put into the hands of each pupil, together 
with the specimens themselves. 

The general plan of study is as follows: — 

1. Directions are given for collecting and preserving the 
specimens. 

2. The live animal is studied. 

3. The external features are noted. 

4. The animal is dissected. 

5. The development of a few forms is traced. 

6. After studying each animal, its relations to other animals 
are considered (classification). 

The aim is, not to describe for the student, thus robbing 
him of the opportunity to develop his own powers of 
description, but to name the parts, telling merely enough 
to enable him to recognize and apply the names to them. 
This makes a real connection between words and things. 

It is thought best for the student to make many of the 
definitions for himself. A definition, thought out by the 



VI INTRODUCTION. 

student himself, imperfect though it be, is of more value 
to him than a perfect definition learned from a book, which 
often appeals to mere memory. Definitions made in the 
way these pages require are good as far as they go : they 
should be corrected and supplemented by the instructor. 
It develops a boy more to earn a dime than to receive a 
dollar as a gift. 

If the main object of this study is the mere acquisition 
of facts, full descriptions of most animals can be elsewhere 
obtained ; but if the more important part in education is to 
lead the pupil to see and think for himself, then some such 
method as this should be used. 

The underlying object in all our teaching is to make 
seeing, thinking, self-reliant, honest men and women. All 
branches of natural science, rightly pursued, are powerful 
means to this end* 

" The feeling is becoming general that practice must be 
united with theory, in the education of young men, or the 
best results of education are lost. The powers and faculties, 
instead of being educated — drawn out and developed — 
are crushed under a mass of merely memorized facts and 
theory, and at the end of his educational course the young 
man finds himself unfitted for the work of the actual world, 
and has to unlearn, and learn again, before he can find the 
path to success. 

" This feeling has resulted, in Germany, in the object- 
teaching of Frcebel ; in Russia, in that celebrated system 
wherein practical work is united with the theoretical 
teaching, which already shows such important results ; and 
in the United States, in the building of workshops and 
laboratories for the use of students in our higher schools 
and colleges." 



INTRODUCTION. Vll 

The order in which the animals are presented has been 
determined by the following circumstances : — 

The work in zoology has usually begun with the fall 
term. At this time insects are abundant, and many kinds 
may be easily collected; they therefore serve well to show 
how animals are classified. The leading principles of 
classification having been taken up in connection with 
insects, no other group is so fully dwelt upon. 

By beginning at this time, the transformations of the 
butterfly may be followed through during the school 
year. 

Insects are attractive ; from insects the student passes on 
to forms which, if taken up at first, would perhaps be 
distasteful to him. Thus it is found that the most squeam- 
ish pupils gradually become accustomed to the free handling 
of all forms of animals. The subject need not be presented 
in its least attractive form at first. 

After devoting considerable time to insects, the student 
takes up the crayfish, earthworm, clam, snail, a few proto- 
zoans, a snake, a fish, a frog, a bird, and a mammal. This 
order of study has been found convenient, but the order is 
not a matter of great importance ; the general principle 
should be, — study what comes to hand. "He is a good 
naturalist who knows his own parish thoroughly." 

Special stress is laid on devising cheap appliances fo* 
collecting, preserving, and dissecting specimens. 

These directions make no pretence of being complete 
dissecting guides, but have been adapted to the ability of 
ordinary pupils in the second year of a high school course, 
and to the time allowed this study. 



Vlil INTRODUCTION. 



TO THE SCHOOL BOARD. 



For practical work in natural history the teacher needs 
a room in which is but the one class with which he is at 
work. This room should be provided with plain tables 
having drawers in which pupils may keep dissecting instru- 
ments, drawing materials, and specimens for study. 

This work is greatly aided by having a water supply in 
the room where the work is done ; this is not only a very 
great convenience to the teacher, but the pupils are much 
more ready to take hold of slimy specimens and the work 
of dissecting, if they can wash their hands conveniently 
before passing to recitation or study room. 

The teacher cannot do justice to this kind of work if he 
has recitation after recitation continuously through the day; 
time is needed in which to prepare dissections which are too 
difficult for the students to make, or for which they have 
not the time ; to arrange the material so as to save time 
when the class has assembled, as well as to clear away 
afterward, and be in readiness for another class. The fol- 
lowing has proved a good arrangement : in a school having 
three recitation periods in each half day the middle period 
of each half day is " vacant," Le., no class comes to the 
teacher of science at this hour; but this time has been very 
far from vacant. 

It is much better to buy several low-priced microscopes 
than one expensive one. 

TO THE TEACHER. 

Do not set out with the intention of finishing this book 
in a given time ; zoology is the study of animals ; study 
animals as long as the time allows, trying to learn as much 



INTRODUCTION. IX 

as possible from a few typical forms ; this will give a better 
view of the animal kingdom than reading many books con- 
cerning many animals. 

Take the study of the grasshopper as an example. The 
first day put the specimens into the hands of the pupil, or, 
better, have him bring his own specimens ; with the aid of 
his dissecting guide he studies the whole hour; the teacher 
goes about, helping those who need, giving directions as to 
use of instruments, etc. Notes and drawings should be 
made in a scratch-book ; many a pupil says, " I cannot 
draw"; ask him to do his best; praise his work if you can; 
suggest how he can do better. The next day question the 
pupils on what they have seen ; perhaps half the hour, or 
less, will serve to bring out what has been discovered on 
the preceding clay. As soon as what has been seen is brought 
out, go on with the study of the specimens. 

After questioning on all the work, call for carefully made 
drawings and descriptions in a permanent note-book. A 
systematic arrangement of these notes should be insisted 
on ; but each pupil should be allowed to follow his own 
plan as far as possible : encourage individuality. 

The name of the study, and of the pupil, should be on a 
white card, or paper, pasted on the outside of the cover. 
An index of the notes should be made, as the work pro- 
gresses, on the inside of the back cover. 

If a rubber band be slipped over the front cover and 
the pages already examined, much time will be saved in 
looking over the books, as they are handed in from time to 
time. 

Urge the pupils to do as much as they will to procure 
specimens for class work, but have in reserve a good sup- 
ply of material. The school should have a supply of alco- 



X INTRODUCTION. 

hol. One boy may live near a creek where he can easily 
get crayfishes or clams for the whole class ; another may 
happen on a lot of beetles. At the beginning of the work 
ask them to carry boxes or bottles, and be on the lookout 
for specimens ; in this way they will learn more, and lighten 
your work. But do not neglect class excursions ; go out 
after school with as many as will accompany you ; have 
picnics on Saturdays with them. 

Let each pupil be required to make a small collection of 
insects ; it is well to urge each pupil to select some order 
or family of insects for special study. Written or oral 
reports of such observations are helpful, and serve to vary 
the work. If there be time, let the pupils select some of 
the following subjects for investigation and reading : the 
chinch bug, silk-worm, bark louse, army worm, cut-worm, 
potato worm, mosquito, gall fly, ichneumon fly, Hessian fly, 
cicada, locust, cochineal, May fly, June beetle, cockroach, 
firefly, daddy-long-legs, plant louse, bed-bug, louse, tick, 
jigger, flea, wasp, honey bee, ant, cabbage worm. Compare 
these with the types studied. Ask the questions : What 
insects are injurious to man ? How can we get rid of 
them ? What insects are beneficial ? How can we best 
propagate them ? 

Make blow-pipes for the students by drawing glass tubes 
to a fine point, rounding the sharp edges in the flame, so 
they will not cut. Tip with sealing wax a lot of bristles, 
both black and white, for probing. Have a good supply of 
cigar-boxes. At the beginning of the oyster season ask a 
restaurant keeper to open oyster cans on the side and save 
them for you ; use these for dissecting pans, as described 
under "the crayfish." 

It may be better for the teacher to make the dissection 



INTRODUCTION. XI 

of the snake, turtle, and a few of the forms that cannot 
usually be obtained in sufficient numbers to supply the 
whole class, and to make some of the finer points clearer, 
especially when the time is short ; but each pupil should 
do most of this work independently, with occasional sug- 
gestions from his teacher. 

If the school does not furnish a microscope, get one 
yourself. 

TO THE STUDENT. 
For this work you need : — 

1. A small pair of forceps. 

2. A small pair of scissors. 

3. A knife. 

4. Two dissecting needles, made by thrusting the eye 
end of a large needle into the end of a pen-holder. 

5. A hard pencil for drawing. 

6. A good pair of eyes. 

Keep these all sharp, especially number 6. 

7. A lens, such as the three-legged lens, or the linen- 
tester. 

8. A scratch-book in which to take notes while studying 
the specimens. Keep this and number 5 in the 
drawer of your work table. 

9. A note-book, in which descriptions of the animals 
studied should be carefully written in ink. 

10. A bottle of mucilage (for every four students). 

11. A quart fruit-jar. 

In drawing, first trace the outlines ; then if these seem 
correct when carefully compared with the object, make the 
lines heavier. Avoid shading. See Morse's " First Book 



xii INTRODUCTION. 

of Zoology" for models of simple drawings. Draw no 
line that does not correspond, as closely as you can make 
it correspond, to something in the object before you. 
Look closely at the object before you put pencil to 
paper. 

In dissecting, follow the directions minutely : they are 
made with care, so as to save time, labor, and material. 

COLLECTING INSECTS. 

Make an insect net as follows : get a light wooden han- 
dle four feet long, and the same length of stout brass wire ; 
bend the wire into a ring a foot in diameter, cut a notch 
in the end of the handle, cross the ends of the wire in the 
notch, and bend the ends so they will run close along the 
handle for six inches; half an inch from the end of the wire, 
bend it at a right angle, and drive into the handle ; then 
wrap tightly with fine wire. 

The ring may be made of a barrel-hoop by steaming it 
till flexible, and bending along the handle and nailing 
firmly. Sew to this ring a bag of thin muslin, twenty 
inches deep. 

The net is used for capturing strong flying insects, such 
as butterflies and dragon-flies, and for sweeping over the 
tops of bushes and grass. When one of the strong fliers 
is taken by the net, the handle should be instantly twisted 
to throw the bag over the ring and prevent escape. 

Butterflies may be killed by pinching the thorax between 
the thumb and finger; fold a two-inch square of paper 
cornerwise, put the butterfly in the fold, and again fold 
the edges and corners. A better method of killing butter- 
flies is as follows : Pack cotton two inches deep in the 
bottom of a Mason fruit-jar ; trim wire gauze to fit closely 



INTRODUCTION. Xlll 

and press it down on the cotton ; saturate, or nearly so, 
the cotton with chloroform just before starting out to 
collect. 

For killing most insects use a cyanide bottle, prepared 
thus : get a wide-mouthed bottle with a glass stopper, or 
tight cork ; place in it two or three pieces, as large as 
caramels, of cyanide of potassium ; this is a very violent 
poison, even its fumes being deadly ; it should be handled 
as little as possible, — pick the pieces up in paper, — and 
should be labeled "Poison" and kept away from children 
and ignorant persons. Mix plaster of Paris and water to 
a thin paste, and pour over the cyanide, covering the 
lumps half an inch deep. Let the bottle stand uncorked 
a day to dry ; the plaster hardens, but, being porous, 
allows the poisonous fumes to rise ; after drying a day it 
should be kept tightly corked. 

When an insect is in the net, the bottle may be un- 
corked, pushed into the net and over the insect, and the 
insect pushed into the bottle by the cork, thus avoiding 
stings, as well as injury to the insect. 

Hard insects, as beetles, bugs, and grasshoppers, may 
be put at once into alcohol. If not used soon, they will 
thus be better kept. 

Many insects, such as bees and beetles, may be taken 
from flowers by quickly pushing them into the bottle with 
the stopper. 

An umbrella is very useful in collecting certain forms 
of insects. Hold the umbrella spread and inverted 
under the branches of trees and shrubs, and beat the 
branches with a stick, or jerk with the handle, if it has 
a hook. 

A lamp, by an open window, has often been found too 



XIV INTRODUCTION. 

good a means of attracting insects. Some of the most 
beautiful moths fly only at night. 

Look for beetles under logs, boards, and under the bark 
of old logs and stumps. Look in ponds for insects and 
their larvae. Treeless meadows and deep forests are not 
as good places for insects as gardens, the edges of woods, 
and the banks of streams and ponds. Collect cocoons and 
larvae, as well as caterpillars, and keep them to see what 
they become. It is well to carry several small boxes in 
which to put such specimens, and insects that have been 
killed in the cyanide bottle, that they may not become 
bruised. 

MOUNTING INSECTS. 

For mounting insects get shallow cigar-boxes. Special 
pins, called insect pins, are made for this work, but com- 
mon pins will serve. In the bottom of the box tack small 
pieces of cork, made by slicing an ordinary cork parallel 
to its ends. Have the insects about two-thirds of the way 
up the pin. Pin beetles through the right wing cover. 
Pin butterflies with the wings spread, and pin through 
the side of the body to show the position when at rest. 
If the insect has dried, it may be softened by wrapping in 
a wet cloth, in the case of hard insects as beetles and 
grasshoppers ; for softening butterflies, put a wad of soaked 
paper into a fruit jar, cover this with dry paper, and put 
in the butterflies still in their papers. Having softened 
the insect in this way, it may be pinned to a piece of cork 
or a pin cushion, and the wings having been stretched, 
they may be pinned in this position, and so kept till dry. 
For holding the wings in place cut small triangles of thick 
paper, thrust the pins through these triangular papers ; and 



INTRODUCTION. XV 

setting the pin so that the pin itself shall keep the wing from 
moving forward or backward, so regulate the height of the 
three-cornered papers that the wing may be held at the 
proper height. A setting board may be made as follows : 
two boards, sloping toward each other, and half an inch 
apart, are fastened to a wide board as a base. The chan- 
nel, or groove, between them should be half an inch deep, 
and a strip of cork fastened to the bottom for holding the 
pins. Pin through the body of the insect, and, the body 
extending along the groove, let the wings rest on the 
smooth, upward-sloping sides. Place the wings as desired, 
lay narrow strips of paper over them and pin the strips 
down. As the wings extend slightly upward, and dry in 
this position, they will be less likely to droop after perma- 
nent mounting. Draw the wings of butterflies forward, 
in setting, till the hind margins of the fore wings form a 
straight line. Let this rule apply to any spread insect. 
Pin a beetle and a grasshopper side by side to show the 
difference in the position of the wings, both folded and 
expanded, and the different manner of folding the wings. 
The name of the insect, date, and place of capture, should 
be written on a small slip of paper and kept on the pin 
below the insect. 

In each box of insects place a piece of camphor to pro- 
tect from injurious insects. 

BREEDING CAGES. 

Take a starch box or chalk box with a sliding cover ; 
cut off three inches from one end of the cover; slide this 
short piece of cover into the farther end ; set the box on 
this end and put in three inches of soil; insert a sliding 
glass cover which projects a little above the top of the 



XVI INTRODUCTION. 

box. Put in this box some larva, say a potato worm ; feed 
it daily with the leaves on which it was found feeding ; 
keep the soil moist, and, if no change takes place before 
cold weather, remove to a cellar and keep till spring. 
Any good-sized glass jar will serve as a breeding cage, as 
a candy jar, fruit jar, or battery jar, with a piece of tin 
laid on as a cover. A jelly glass makes an excellent 
breeding case for eggs and young larvae. 



Peagtical Zoology. 

THE GRASSHOPPER. 

THE PARTS OF THE BODY. 

1. The foremost, or anterior, part is the head. 

2. The middle part is the thorax. 

3. The hinder, or posterior, ringed part is the abdomen. 

THE HEAD. 

1. Notice its shape and mode of attachment to the thorax. 

2. Two slender projections, the feelers, or antennae. 
Observe how and where they are attached to the 
head. Use a lens to count the parts, or segments, 
of which each antenna is composed. 

3. Note the situation and shape of the eyes. Examine 
one of the eyes under a microscope, using a one-inch 
objective ; make a drawing of what you see. These 
eyes are compound, and each of the parts is called a 
facet. 

4. Just in front of the compound eyes look for a pair of 
simple eyes, the ocelli. Find a third ocellus on the 
head, using a lens if necessary. 

5. At the lower part of the front of the head is a mov- 
able flap, the upper lip, or labrumj raise it with the 



2 PRACTICAL ZOOLOGY. 

dissecting needle. Observe how it is hinged ; cut or 
break it off. 

6. This lays bare the true jaws, or mandibles. Examine 
their black, toothed tips with a lens; find, by prying, 
how they move. Study their action in the live grass- 
hopper, raising the labrum. Study carefully the way 
in which they move, and how they are hinged; then re- 
move with the forceps, and again examine thoroughly. 

7. Back of and between the mandibles is the brown 
tongue. 

8. Turn now to the back of the lower part of the head ; 
pry back the lower lip, labium; carefully remove it. 

9. Attached to the base of the labium is a pair of short, 
jointed appendages, the labial palpi. What is the 
relation between the tongue and the labium ? 

10. If the above-named parts have been carefully removed, 
there will remain one pair of appendages, smaller 
jaws, called the maxillae. Make out that each max- 
illa consists of three parts : — 

a. An outer, jointed part, the maxillary palpus. 

b. A spoon-shaped piece covering c. 

c. The brown, in-curved maxilla proper. Examine 
with a lens, then with forceps remove the whole 
maxilla, being sure to get the basal part. 

11. Cut the head off a fresh specimen ; lay it on the table 
and make a careful drawing of the face, naming all 
the parts. 

12. Draw the head as seen from the side. 

THE THOEAX. 

1. The wide collar, or cape, back of the head is the 
prothorax j make a drawing of it as seen from the side. 



THE GRASSHOPPER. 3 

2. The remainder of the thorax is formed by the union 
of two parts, each bearing a pair of legs, the part to 
which the middle pair of legs is attached being the 
mesothorax, the hinder legs arising from the meta- 
thorax. Look for the line separating these two parts 
of the thorax. 

3. Look just above the second pair of legs for a narrow 
opening, guarded by a pair of lips, which, in the live 
grasshopper, keep separating and coming together; 
this is a breathing pore, or spiracle. Look for another 
spiracle on the soft skin under the posterior edge of 
the prothorax on each side. 

4. Carefully compare the prothorax, mesothorax, and 
metathorax. 

THE WINGS. 

1. Notice the position of the outer wings, and their mode 
of overlapping. 

2. With the forceps seize one of the outer wings by its 
lower edge, near the anterior end, and draw it hori- 
zontally forward, till it makes a right angle with the 
body, and pin in this position. Seize the inner wing 
by its lower edge near the posterior end, and pull 
forward to its fullest extent, observing how it is 
folded ; pin this wing as expanded, and make a draw- 
ing of both wings as thus seen. Cut a piece of paper 
the same size and shape as the inner wing, and fold 
it as the inner wing is folded. 

3. The framework of the wings is composed of veins. 

4. Compare the inner and outer wings in : — 

a. Size. 

b. Shape. 



I PRACTICAL ZOOLOGY. 

c. Color. 

d. Texture. 

e. Position, both when at rest and in motion. 
/. Use. 

THE LEGS. 

1. Note their number, arrangement, and mode of attach- 
ment. 

2. Study carefully one of the hind legs. 

a. A short segment near the body, the coxa. 

b. The big segment is the femur. 

. c. The slender segment is the tibia. 

d. The remainder is the foot, or tarsus; count its 
segments, and examine thoroughly, using a lens. 
Remove a hind leg, and make a drawing show- 
ing all these parts. 

e. Examine the joint between the femur and tibia, 
moving the parts back and forth. Note, also, 
how these parts fit together when the leg is 
drawn up. 

■f. In how many ways does the grasshopper travel? 

In what order are the legs moved in crawling ? 
g. Grasshoppers make a shrill sound (stridulation) 
by rubbing the inner surfaces of the hind legs 
against the outer wings. 
h. In what different ways does the grasshopper keep 
from slipping when it jumps ? Remove the legs 
and wings ; make drawings of the thorax as seen 
from the side, from above, and from below. 



THE GRASSHOPPER. 



THE ABDOMEN. 



1. Count the abdominal rings. 

2. Observe two grooves running along the under surface 
of the abdomen. The under part of the abdomen, 
included between these grooves, is the sternum, the 
side of the abdomen is called the pleurum, and the 
upper part is the tergum; the corresponding parts of 
each separate ring are the sternite, pleurite, and 
tergite. 

3. Just above the groove which separates the sternum 
from the pleurum is a row of small holes, the breath- 
ing pores, or spiracles; count them. 

4. In a live specimen, watch the movements of breathing. 
All insects breathe by means of a complicated system 
of air tubes, the tracheae, which branch from the 
spiracles throughout the body. Can the grasshopper 
be drowned by holding its head under water? Connect- 
ed with the air tubes, in grasshoppers and other strong 
flying insects, as bees and flies, are large air sacs, which 
fill with air, and are said to aid, like little balloons, 
in keeping the insect in the air. By carefully cutting 
away the roof of the abdomen, these air sacs may be 
seen, marked by their white walls ; the white air 
tubes, or tracheae, may also be readily seen. 

5. Under the bases of the wings, on the first abdominal 
ring, is a pair of thin, shiny, oval membranes, the 
tympana, or ear drums. The inner surface of each 
tympanum is connected with a nerve ; but several 
investigators have denied the auditory nature of this 
apparatus. 

6. The abdomen of the female ends in four points : in 



6 PRACTICAL ZOOLOGY. 

laying the egg these points are first pressed together, 
then thrust into the ground, and then separated ; this 
process is repeated till a hole is made, sometimes as 
deep as the abdomen is long, at the bottom of which the 
eggs are deposited, passing out between the four points 
of these egg guides, which together are called the 
ovipositor; compare the inner and outer surfaces of 
these egg guides. The males are smaller than the 
females. Draw the abdomens, as seen from the side, 
of both the male and the female. Take now an entire 
specimen and draw a side view of it. 

INTERNAL STRUCTURE OF THE GRASSHOPPER. 

This work would better be done after the student has 
dissected the crayfish. Dissect under water with the dis- 
secting pan as described under the " crayfish." 

1. Get a large female grasshopper, freshly killed. Cut 
off the wings, and place the specimen, back upper- 
most, in the dissecting pan; pin the hindermost ring 
of the abdomen firmly to the bottom of the dissecting 
pan; turn each hind leg outward and pin down. 
With sharp, fine-pointed scissors, cut through each 
side of the roof of the next to the last abdominal ring; 
lift, with the forceps, the cover of this ring; continue 
the cut forward, on each side of the abdomen, pulling 
the tergum upward and forward as it is loosened. 
Thus carefully unroof the whole abdomen. 

2. The heart is a delicate tube, running along just 
under the tergum, and probably was torn away with 
the tergum. 

3. On each side there should now be seen a row of air 
sacs, with their white air tubes. 



THE GRASSHOPPER. 7 

4. In the anterior part of the abdomen a mass of yellow 
eggs is usually to be found ; this mass may be easily 
separated into two parts, right and left, from each of 
which a tube, oviduct, leads to an opening between 
the parts of the ovipositor. 

5. Under the eggs is the dark intestine, running length- 
wise. 

6. Remove the roof of the thorax; more air sacs should 
be found here. In the upper part of the thorax are 
the white muscles which move the wings. Remov- 
ing these muscles exposes more of the digestive tube ; 
as the food is swallowed, it passes upward in a brown 
tube, which soon turns backward into the thorax ; in 
the prothorax, the enlargement is the crop, in which 
is produced the dark liquid which the grasshopper 
ejects from the mouth when held captive. The crop 
may be removed, washed, split open and examined 
under the microscope with a half-inch objective to show 
the rows of hooked teeth with which it is provided. 
A little further back the digestive tube is surrounded 
by a set of double cone-shape pouches, which extend 
parallel with the main channel of the digestive tube. 
These are the gastric caeca. Behind them is the 
stomach, followed by the intestine. The products of 
digestion pass through the coatings of the digestive 
canal, and mingle with the currents of blood which 
pass along the ventral and lateral parts of the body. 

7. The colorless blood enters the heart through holes 
along its sides ; blood is sent from the heart into the 
veins of the wings. These veins are hollow tubes, 
and though they convey blood, are very different 
from the veins in our bodies. Air tubes run along 



8 PRACTICAL ZOOLOGY. 

the centre of the larger veins, and give air to the 
blood as it flows. 
8. The nervous system of the grasshopper consists mainly 
of a white cord extending along the floor of the whole 
body cavity. In most of the abdominal rings the 
nerve cord has enlargements called ganglia, from 
which nerves branch to the surrounding parts. 

THE DEVELOPMENT OF THE GRASSHOPPER. 

The egg hatches out a little grasshopper, at first with- 
out wings. As it grows, it sheds its skin (moults) several 
times. In moulting, the skin splits along the back of the 
head and thorax, and the insect works its way out. At 
first the newly hatched insect is very soft ; the writer has 
seen a grasshopper bend its tibia double in the effort of 
pulling out of the old skin; but the tibia soon straight- 
ened and hardened, showing no signs of injury. 

For descriptions of the grasshopper, see Packard's " Zool- 
ogy," Packard's " Guide to the Study of Insects," Brooks' 
" Handbook of Invertebrate Zoology," "The Rocky Moun- 
tain Locust," in First Annual Report of U.S. Entomologi- 
cal Commission, 1877 (issued 1878), Comstock's " Guide 
to Practical Work in Elementary Entomology." 

GRASSHOPPER CARD. 

Take a card six inches by four. Make a faint mark 
lengthwise in the middle to aid in placing the parts sym- 
metrically. Separate the parts of the grasshopper, and 
paste them on the card in their proper order. Before be- 
ginning, plan the whole arrangement. First, cut off the 
head ; leaving a central place for the head, remove the 
mouth parts, pasting each to the card as it is removed. 



THE CRICKET. 



In separating the parts use the forceps, being careful to 
get hold of the very base of each piece ; then, holding 
each part with the forceps, dip the side that is to go next 
to the paper into the mucilage, and carefully place just 
where it is to stay. This method avoids smearing the card. 
Avoid getting too much mucilage. The mouth parts should 
surround the head ; the wings should be opposite the parts 
to which they were attached, as also the legs. The legs 
should be separated to show all the segments; the thorax 
should be separated into its parts, but the abdomen would 
better be kept entire. As the parts become very brittle 
when dry, it is well, if the card is to be kept, to make a 
little bridge of a strip of paper, on which to string the 
rings of the thorax and abdomen. The soft parts should, 
of course, be removed. 



THE CRICKET. 

1. In what are the cricket and grasshopper alike? 

2. In what respects do they differ ? 

3. The female cricket has a long, slender ovipositor. 
Compare its parts with the parts of the grasshopper's 
ovipositor, picking them apart with a dissecting 
needle. Use a lens. 

-1. A pair of tapering, jointed projections from the abdo- 
men are the stylets. 

5. Compare the wrings of the male and female. Look on 
the under surface of the outer wings of the male for 
a vein, running crosswise, near the anterior end, which 
has on it a row of teeth. By rubbing this file on the 



10 PRACTICAL ZOOLOGY. 

veins of the other wing, the cricket makes its chirping 
noise. Watch crickets to see how the wings are man- 
aged during this process. 

6. With a lens look for the so-called hearing organ on 
the tibia of the fore leg. 

7. Make a drawing showing all that can be seen from 
above (dorsal view), and naming all the parts shown. 

Grasshoppers and crickets both belong to the order of 
insects called Orthoptera, or straight-winged insects. 



THE BUMBLE BEE. 

1. Find three ocelli on the top of the head. How are 
they arranged ? 

2. Describe the antennae. 

3. The mouth parts : — 

a. A pair of true jaws. 

b. The long, hairy tongue. 

c. Above the tongue the two blades of the maxillae. 

d. Below the tongue the thin, narrow labial palpi. 

The last three form a proboscis ; pick the parts asunder, 
and make a drawing of the front of the head, showing all 
these parts. 

4. How does the bee take its food? Is the honey stored 
by the bee the same as when taken from the flower ? 

5. Compare the segments of the legs with those of the 
grasshopper. How does the bee get pollen ? What 
does the bee do with the pollen ? 



THE BUTTERFLY. 11 

6. Examine the wings; compare the front and hind 
wings. 

7. Get a bumble bees' nest ; examine the contents of the 
cells, and note the different stages of development of 
the young bees. 

8. The sting is a modified form of ovipositor. Near its 
base are poison glands, and a sac for storing the 
poison. 

9. How do bees compare with other insects in intelli- 
gence ? 

10. Eead the account of the habits of bumble bees, and of 
honey bees, in Packard's " Guide to the Study of 
Insects." 

11. Ants, bees, and wasps belong to the order Hymenop- 
tera, or membrane-winged insects. 



THE BUTTERFLY. 

The large, brown " milkweed butterfly," with dark 
markings along the veins of the wings, is a good one to 
study. 

1. Notice the position of the eyes, and their relative size. 

2. Where are the antennae attached? Compare with 
those of the grasshopper. 

3. The short projections in front of the head are the labial 
palpi. 

4. Between the palpi is the coiled sucking tube ; uncoil 
and examine it. 

5. The wings : — 



12 PRACTICAL ZOOLOGY. 

a. Their shape and their mode of overlapping. 

b. The dark, shiny veins ; where are they strongest ? 

c. Scrape some of the scales off a wing; examine 
under a high power of the microscope, making 
drawings. 

d. Examine a piece of a wing, with the scales on it, 
to see how they are attached and arranged. Look 
at a part of the wing where the scales have been 
removed. 

6. Spread the wings of the butterfly, and draw them as 
seen from above. 

7. Examine the legs, and compare their use in this insect 
and others. 

8. Make a drawing of the butterfly as seen when at rest, 
naming all the parts visible. 

9. Compare the colors and markings of the upper and 
lower surfaces of the wings. 

10. Carefully compare a moth and a butterfly. 

11. Butterflies and moths belong to the order Lepidoptera, 
or scaly-winged insects. 

The orders of insects are divided into families; this 
butterfly belongs to the family Nymphalidae. 

Families are divided into genera; this butterfly belongs 
to the genus Danais, 

Genera are divided into species; this species is archip- 
pus. So this butterfly belongs to the class, Insecta; order, 
Lepidoptera; family, Nymphalidae; genus, Danais; species, 
archippus. 

The males are distinguished by an elevated black spot 
along one of the veins, near the middle of the hind wings. 

Where is this butterfly found most abundantly? 



THE BUTTERFLY. 13 

Consult French's "Butterflies of the Eastern United 
States," for finding the names of butterflies. 

DEVELOPMENT OF THE CABBAGE BUTTERFLY. 

The cabbage butterfly is small, yellowish beneath, paler 
above, with black tips to the anterior wings. The male 
has one round, black spot only on each upper wing, while 
the female has two, and sometimes three. 

1. Open the abdomen and look for eggs. They are yel- 
low, oval bodies ribbed lengthwise, with cross mark- 
ings on the ridges, resembling stunted ears of yellow 
corn. Look also for these eggs on cabbage leaves, or 
where these butterflies are seen hovering. Watch the 
butterflies closely as they light on the cabbage leaves, 
to see the egg deposited on the leaf ; on which side of 
the leaf are the eggs usually laid? How are they 
fastened to the leaf? Make a drawing of the egg as 
found attached to the leaf. 

2. Get a chalk box with a sliding cover ; substitute a 
glass cover a little longer than the box. Cut windows 
in the sides of the box and fasten wire gauze over 
them. Keep the box on end, so that the door will keep 
closed, yet may be easily opened. Put into this box 
a cabbage leaf with eggs on it ; examine several times 
a day. What becomes of the egg ? In another box, 
similarly arranged, put some large cabbage worms ; 
give them fresh leaves every day, and keep the box 
in a light, well -ventilated room. Watch closely, and 
keep record of the date of the beginning of the ex- 
periment, and note the date of any change ; describe 
carefully all actions and changes in the worms. 
Make careful drawings of each stage of growth : — 



14 PRACTICAL ZOOLOGY. 

a. The egg. 

I. The larva, at different stages of growth; keep 
one worm in a cage by itself, and make a draw- 
ing every third day. 

c. The pupa, showing how it is suspended. 

d. The perfect butterfly. 

3. The cabbage butterfly belongs to the family Papilion- 
idae, genus Pieris, species rapae. 

There are several species of the genus Pieris, just as 
there may be several in one family among us ; as in a 
directory we read : " Smith, Charles," " Smith, Edmund " ; 
so we read : Pieris rapae ; Pieris protodice. 

What is the meaning of the word " rapae " ? 

For account of the cabbage butterfly, see " Report of the 
Entomologist" in the "Report of the Commissioner of 
Agriculture for the year 1870." 

Occasionally a larva will fail to go through its proper 
changes; this is generally caused by some parasite, the 
most common of which is an ichneumon larva. The adult 
of some kind of ichneumon fly stings the cabbage worm 
and lays its eggs in its body ; these eggs hatch out as 
worms and live on the juices and tissues of the cabbage 
worm, till it dies from exhaustion (though the cabbage 
worm often lingers, and the parasitic larvae complete their 
transformation first), and the parasitic larvae become pupae, 
and hatch out as perfect ichneumon flies. 

Look for holes in pupae which fail to complete their 
transformation ; often holes may be found in them where 
the ichneumon flies have made their escape. If a pupa 
blacker than usual be found, put it in a vial, or pill box, 
and catch the ichneumon flies as they emerge. 



THE HOUSE FLY. 15 

THE HOUSE FLY. 

THE PARTS OF THE BODY. 

1. The head, the foremost, or anterior part. 

2. The thorax, or middle portion. 

3. The abdomen, the hinder, or posterior part. 

THE HEAD. 

1. Examine the eyes with a strong lens, and under a low- 
power of the microscope, to discern its parts or facets. 
Such an eye is said to be compound, and in the fly is 
composed of about 8000 parts ; what shape have the 
facets ? 

2. Cut off the head, lay it on a glass slide, and with a 
one-inch objective examine the short antennae in front 
of the head. 

3. Look on the top of the head for simple eyes. 

4. With a lens examine the under part of the head to 
see the tongue. How does it move ? Remove it and 
look at it with a one-inch objective. How is it used? 

THE THORAX. 

1. How many legs are there ? To what are they attached? 
How many segments has each leg ? 

2. The wings ; how many are there ? Back of each wing 
find a short membrane, the winglet. Xote the folded 
portion connecting the wing and the winglet. 

3. A little further back are two slender knobs project- 
ing on stalks like pins; these are the balancers, and 
are considered as representing the hinder wings found 



16 PRACTICAL ZOOLOGY. 

in most insects. Note the effect of removing the 
balancers. 

4. The wings describe a figure 8 in flying, and make over 
300 revolutions (i.e., go up 300 times and down 300 
times) in a second. 

5. On each side of the thorax, just back of the head, find 
a narrow opening with yellow, lip-like border; ex- 
amine closely with the aid of lens and microscope. 
It is a breathing pore, or spiracle. 

THE ABDOMEN. 

Are there spiracles on the abdomen? How many rings 
has the abdomen? Draw the fly as seen from above, 
dorsal view. 

The house fly lays its eggs about stables ; after a day or 
two the eggs hatch out as little worms, or maggots, which 
eat voraciously and grow rapidly ; in about a week they 
cease eating, become dry and brown, resemble a seed, and 
neither move nor grow ; from this pupa the fly emerges. 
The adult fly is short lived, though some live over winter. 
Watch the development of the egg which the flesh fly lays 
on meat and dead animals. How many kinds of flies do 
you know ? How do they differ ? How does the fly walk 
on the window pane ? Examine the feet. In what order 
does the fly move its feet in walking ? For the study of 
this point, take a fly that is sluggish from cold, or from 
partial drowning. Do flies, on the whole, injure man, or 
benefit him? Flies belong to the order Diptera, or two- 
winged insects. What other insects have but two wings ? 
Read the Muscidse in Packard's "Guide to the Study of 
Insects." 



SQUASH-BUG. — BEETLE. 17 



THE SQUASH-BUG. 

1. Find the sucking tube bent back under the thorax. 

2. Are there both simple and compound eyes ? 

3. What peculiarities of the prothorax ? 

4. Draw a dorsal view, showing how the wings overlap. 

5. Draw the squash-bug's wings out at right angles to 
the body, and make another drawing showing how 
the outer wings appear when extended, and how the 
inneT wings are disposed. 

6. Draw a ventral view. 

Look for eggs. Compare young and old squash-bugs. 
Squash-bugs belong to the order Hemiptera, or half-winged 
insects. What is the propriety of this name? Insects 
belonging to this order are the only ones that are properly 
called "bugs." 

See account of the squash-bug in Harris' " Insects In- 
jurious to Vegetation." 



THE BEETLE. 

1. What are the characters that appear peculiar 'at first 
sight ? 

2. Note the position, shape, and range of vision of the 
eyes. 

3. The antennae, their attachment, parts, and mode of 
extension. 

4. A small upper lip, the labrum. 



18 PRACTICAL ZOOLOGY. 

5. A pair of strong jaws, the mandibles, often very large, 
and projecting forward as pinchers, or " horns." How 
do they move ? 

6. Back of these are two small jaws, the maxillae, bear- 
ing a pair of jointed appendages, the maxillary palpi. 

7. Back of (posterior to) the maxillary palpi is another 
pair of similar appendages, the labial palpi. 

8. The part of the body back of the head is the protho- 
rax. Why not call it the thorax ? 

9. Pry up the hard outer wings. How do they meet 
each other? The outer wings are called the wing 
covers, or elytra. In what direction does the beetle 
move the elytra in raising them ? How are they held 
during flight? Do they rise vertically? 

10. How are the inner wings folded? Compare the inner 
and outer wings in length and size. Cut a piece of 
paper of the same shape as the inner wing, and fold it 
as the inner wing is folded. How does the beetle 
perform the act of folding the inner wings? Capture 
live beetles and watch this process. 

11. Make a drawing of the back, with the wings closed ; 
another drawing, with the wings fully expanded, as in 
flight. 

12. Count the segments of the legs. Examine each seg- 
ment closely. Seize the foot of one of the hind legs 
with the forceps, and pull it about in all directions, 
to see how many joints the leg has, and what motions 
are allowed by each joint. The segment nearest to the 
body is the coxa. Then come in order, trochanter, 
femur, tibia, and tarsus (foot). 

13. What marks the line of division between the thorax 
and abdomen ? 



THE DRAGON-FLY. 19 

14. Draw a ventral view on a large scale, showing 
especially the parts of the legs, and the mouth parts. 

15. Watch a crawling beetle, to see in what order the legs 
are moved. 

16. What can you tell of the habits of beetles ? The 
different kinds of beetles, and their development? 
What is a grub? Compare beetles with other insects 
in strength. The large beetles are good insects for 
dissecting, to show the internal structure. Beetles be- 
long to the order Coleoptera, or sheath-winged insects. 

See " Classification of the Coleoptera of North America" 
by LeConte and Horn. 



THE DRAGON-FLY. 

1. Compare the shape and relative size of the parts of 
body with those of other insects. In some dragon- 
flies the eyes have as many as 12,500 facets each. 

2. What kind of mouth parts has the dragon-fly ? 

3. How does the dragon-fly compare with other insects 
in power of flight? To what bird should the dragon- 
fly be compared in its habits ? 

4. Has the dragon-fly a sting? Is it dangerous to man 
in any way ? 

5. Watch the dragon-fly dipping the end of its abdomen 
into the water to lay its eggs. Compare the oviposi- 
tor with that of the grasshopper. 

6. The larva of the dragon-fly may be found on the 
bottoms of ponds and streams, and is very noticeable 
on account of its wide head and prominent eyes, wide 
abdomen, and short wings. 



20 PRACTICAL ZOOLOGY. 

7. When the larvae are ready to transform, they crawl 
up out of the water, their skins split along the back, 
and the adult dragon-fly escapes, leaving its dry, 
empty skin, which maybe found clinging to the stems 
of water plants, projecting logs, or rocks. 

8. Draw a dorsal view. 

9. The dragon-fly belongs to the order Neuroptera^ or 
nerve-winged insects. 



REVIEW OF INSECTS. 

Take any insect not yet studied, and examine it thor- 
oughly. Write a full description, and make drawings of 
it. To which of the insects previously studied is this 
most like? To what order, then, does it probably belong? 

Select two pages in your note-book that face each other. 
On the left-hand page make a list of characters common 
to all the insects you have studied, numbering the points; 
on the right-hand page write briefly the characters peculiar 
to each insect. The first list ought to be a very nearly 
correct definition of an insect, as far as external features 
are concerned. The second list should serve as a defini- 
tion of each of the orders of insects. 

All the orders of insects belong to the class Insecta. 

Write now a list, in vertical series, of the orders of in- 
sects studied, with the name of the insect representing 
that order opposite it, and include all within a brace oppo- 
site the word Insecta. 

Read Hyatt's " Insects" (No. VIII. in Guides for Science- 
teaching). See also " Standard Natural History," Vol. II., 
and Saunders' " Insects Injurious to Fruits." 



THE SPIDER. 21 



THE SPIDER. 

Spiders are best preserved in alcohol, as they shrink in 
drying. 

1. The anterior division of the body is the cephalo- 
thorax, or united head and thorax. 

2. The large posterior division is the abdomen. 

3. How many legs are there? To what are they at- 
tached? How many segments are there in each? 
Examine the feet under a microscope. Make a draw- 
ing of one of the feet. Can a spider climb out of a 
tumbler ? Compare it with the beetle in this respect. 

4. With a dissecting needle pry apart the mandibles, 
at the front of the head. Make out the fine, spine- 
like, curved poison fang at the lower end of each 
mandible. 

5. Back of the mandibles find a pair of small jaws, the 
maxillae. 

6. To the maxillae are attached a pair of jointed append- 
ages, resembling a pair of legs, the maxillary palpi. 

7. With a lens look for the simple eyes above the jaws. 
How many are there, and how are they arranged ? 

8. With a lens examine the spinnerets at the posterior 
end of the abdomen. With a pair of forceps hold a 
live spider by one leg, and watch the beginning of 
spinning. Highly magnified, the spinnerets appear as 
blunt protuberances arranged together in pairs, and 
capable of being contracted or expanded. These 
spinnerets are covered with hundreds of jointed hairs, 
which are perforated and through which the web- 
forming material issues. This material is fluid, and 



22 PRACTICAL ZOOLOGY. 

somewhat like the white of an egg. Escaping from 
the body, through hundreds of these openings, the 
strands of this fluid dry almost instantly, and uniting, 
form the delicate, yet comparatively strong, thread of 
the spider. Thus it will be seen that the thread of 
the spider is composed of hundreds of strands, which 
may often be separated just as the fibres of a rope 
may be pulled apart. 
9. Besides trachese, spiders have a so-called lung, com- 
posed of several leaves, into which blood flows, and is 
thus aerated. 

Place the description of the spider alongside the list of 
characters common to insects, and note what features are 
common to the spider and all the insects ; also the points 
wherein they differ. 

Spiders belong to the class Arachnida. Is the young 
spider, when first hatched, like the adult? Study the 
habits of spiders, and their methods of spinning their webs 
and capturing insects. 

Read Emerton's " Spiders, their Structure and Habits," 
and the chapters on spiders in Morse's " First Book of 
Zoology," Packard's "Zoology/' and Packard's "Guide." 



THOUSAND LEGS. 

One form of thousand legs is well known by its cylin- 
drical body, by its numerous, short, hair-like feet, and by 
its habit of coiling its body into a spiral when disturbed. 



THOUSAND LEGS. 23 

1. How many segments has the body? 

2. How many appendages has each segment ? 

3. Make a drawing of the thousand legs. 

4. What are the chief differences between this animal 
and insects ? 

Another common form of thousand legs QLithobius 
americanui) is that called (wrongly) " centipede," or 
(also wrongly) " earwig." It is, when full-grown, about 
an inch long, with a broad, flat head, a brown, shiny back, 
the segments being mostly of about the same size, with 
one pair of jointed appendages to each segment. The 
antennae are many jointed. It is found under boards, and 
about rubbish, and manure heaps, where it feeds on insects 
and earthworms. 

1. Examine the jaws and mouth parts carefully ; how 
many pairs of jaw 7 s are there ? 

2. With a lens examine the legs. How many are there ? 

3. What kind of eyes are there ? How many, and how 
placed? 

4. Arrange the legs so they can be distinctly seen, and 
make a drawing as seen from above. 

5. Make an enlarged drawing of the mouth parts as seen 
from below. 

6. What are the differences between this form and the 
thousand legs mentioned above ? 

7. In what are the two alike? Both belong to the 
class Myriapoda. Carefully compare them with the 
insects, and make a list of points common to insects 
and myriapods ; also a list of the characters which 
insects have and the myriapods do not have ; and a 
list of points peculiar to myriapods. 



24 PRACTICAL ZOOLOGY. 

THE CRAYFISH. 

Get a number of live crayfishes. They are usually to 
be found hidden under stones in the shallow water of 
creeks. Put into alcohol at least three for each student. 
Keep some of them alive in an aquarium — a large pan 
will serve, though the vertical sides of a regular aquarium 
render it easier to watch the movements of these and 
other aquatic animals. Let each student have a live cray- 
fish in a fruit-jar. Examine from above, from the side, 
and from beneath. How many legs does the crayfish use 
in walking ? Frighten the crayfish by suddenly thrusting 
a pencil at it; how does it effect such rapid locomotion? 
Touch one of the eyes with the pencil; what follows? 
Move the pencil slowly toward one of the large claws. 
What does the crayfish eat, and how does it eat ? What 
are its habits ? 

The crayfish and lobster are so nearly alike that these 
directions, though written for the crayfish, will serve 
fairly well for the latter. Use crayfishes that have been 
a short time in alcohol. If lobsters are used, get unboiled 
specimens. 

EXTERNAL PARTS OF THE CRAYFISH. 

1. The united head and thorax are called the cephalo- 
thorax. 

2. The continuous covering of the two is the carapace. 
The projection of the carapace, above and between 
the eyes, is the rostrum. 

3. The hinder, flexible part of the body is the abdomen. 
Count its rings, or segments. Bend (flex) the ab- 
domen, and straighten (extend) it repeatedly, observ- 



THE CRAYFISH. 25 

ing how the segments are jointed together, and how 
they move one upon another. 

Separate the third ring (counting from the front) 
from the rings in front of and behind it. To do this 
hold the cephalothorax and fore part of the abdomen 
firmly between the thumb and forefinger of the left 
hand, with the posterior end of the abdomen projecting 
toward the right hand ; then, grasping the dissecting 
needle firmly with the right thumb and forefinger, 
thrust the point of the needle obliquely forward 
between the third and fourth segments, and work it 
right and left, severing all connection between them 
without breaking either ; with scissors cut the mem- 
brane between the under sides of the rings, and en- 
tirely separate them. In like manner, detach the third 
segment from the second. The ring has these parts: — 

a. The upper part, the tergite. 

b. The under part, the sternite. 

c. The side piece, the pleurite (projecting down- 
ward). 

d. Two appendages, the swimmerets. 

Observe that each swimmeret has a main stalk and 
two branches ; examine these appendages thoroughly. 
Lay the ring on its front side, make the branches of 
the swimmerets diverge enough to appear distinct, 
and make a drawing of the whole ring as seen from 
behind. 

Compare the other segments of the abdomen with 
the third. 

In the mate the appendages of the first and second 
rings are larger than in the female. Other organs as 



26 PRACTICAL ZOOLOGY. 

well as the generative apparatus present differences 
in the two sexes, being modified for the performance 
of special functions in the sexual life, such as the 
differences in color and markings of male and female 
butterflies, and the differences between the wings of 
male and female crickets, already noticed. These 
differences are known as secondary sexual characters. 
Compare the male and female crayfish as regards the 
width of the abdomen. 

Study carefully the structure and action of the tail- 
fin. Its middle piece is the telson, underneath which 
is the external opening of the intestine, the anus. 

Remove the telson, and without disturbing the side 
parts of the tail-fin, separate the sixth abdominal ring 
from the fifth. Now carefully compare this (sixth) 
ring and its appendages with the third ring and its 
appendages. 

Are the appendages of the thorax borne upon rings 
like those of the abdomen ? If so, where are the 
rings? With forceps seize the base of one of the 
hindmost pair of walking legs, and move it back- 
wards and forwards; are these borne on a distinct 
ring? Carefully clean the sternum between the other 
walking legs, and look closely for indications of rings. 

5. With the forceps break away one side of the carapace, 
beginning at the lower edge. This lays bare the 
white, feathery gills. Move the legs of this side 
back and forth, watching the gills. 

6. Study now the hindmost of the walking, or thoracic 
legs. Count its segments. Observe how the first 
segment is joined to the body. Flex the leg as far as 
possible, in every direction, noting the number of 



THE CRAYFISH. 27 

joints, and the motions allowed by each. With the 
forceps seize the squarish, basal segment of this leg, 
and pull off the leg. 

7. Remove in like manner the leg in front of this, again 
being careful to get a firm hold of the short, wide 
segment next to the body. What is the relation 
between the leg and the gill nearest to it? Lay this 
leg on a paper in front of the one previously removed. 
In this way pull off all the legs of one side, from the 
hindmost to the foremost, laying them in order. 
Compare them all with the one first taken. In the 
legs bearing pinchers is there any really new part 
added, or is the pinching apparatus produced by some 
change in a part present in all the legs? How do 
the legs which bear the big claws differ from the 
walking legs ? Compare them, segment with segment. 

8. In front of (anterior to) the big legs are several pairs 
of appendages surrounding the mouth. Probe be- 
tween them to find the mouth. These mouth parts 
are numbered from the front, but on account of the 
way in which they overlap, it is easier to remove and 
study them in the reverse order. 

9. The appendages just in front of the big claws are the 
hindmost of three pairs of jaw-feet, or maxillipeds. 
Gently raise them, to see how they cover the other 
mouth parts. Note that these maxillipeds, or foot- 
jaws, have an inner branch, which meets the corre- 
sponding part of the opposite maxilliped, and an 
outer branch. Observe that both these branches are 
attached to one segment next to the body. Seize this 
basal segment,* and remove the whole maxilliped. 
Compare it with one of the swimmerets of the third 



28 PRACTICAL ZOOLOGY. 

ring of the abdomen. In the same way remove the 
second and first maxillipeds of this side, keeping them 
in order. Are there gills attached to the maxillipeds? 
Is there more than one gill on each leg ? Are there 
other gills than those attached to the legs ? Pick one 
of the gills to pieces under water to determine its 
structure. After removing the gills, look in this 
region for further traces of thoracic rings. 

10. Anterior to the maxillipeds are two pairs of maxillae. 
These are very thin, and lie close to each other, so 
that if great care be not taken, they are likely to be 
pulled off together. Investigate closely, and then, 
inserting the forceps well down, remove them, one at 
a time. Attached to the base of the hinder maxilla 
is a thin, double-spoon-shaped structure, the gill- 
scoop. It lies in the front part of the cavity in 
which the gills are, the gill-chamber. With the 
forceps move back and forth the second maxilla of 
the other side, to see how the gill-scoop is thereby 
moved. The gill-scoop, swinging back and forth, 
pushes the water out of the front end of the gill- 
chamber. The water thus expelled is replaced by 
fresh water, which comes up under the lower edge of 
the carapace, about the bases of the legs; thus the 
gills are constantly bathed with water containing 
a fresh supply of oxygen. 

11. The mandibles are short, hard, toothed, each bearing 
a jointed appendage, which curves around the anterior 
edge of the mandible in a groove. This is the mandib- 
ular palpus. Move the mandible about to see how 
it is hinged. Closely fitting against the posterior 
surface of each mandible is a thin leaf-like structure, 



THE CRAYFISH. 29 

the metastoma. (The metastomata differ from the 
maxillae in pointing outward and in being undivided.) 
Remove it and complete the series of mouth parts, — 
mandible, first maxilla, second maxilla, first max- 
illiped, second maxilliped, third maxilliped. Remove 
the corresponding appendages of the other side, lay 
them in a row facing those of the opposite side, as 
before removal, but not now overlapping each other, 
and make a drawing of the series, naming them. 

12. The long projections in front of the head are the 
antennae. Seize one of them with the forceps, and 
pull about in all directions, to make out the large 
segment, at its base, under the head. On this basal 
segment find a small white cone, with a hole at its 
summit. This is the aperture of the green gland, 
in the head, which acts as a kidney in throwing off 
certain waste products from the body. Remove the 
antenna, with the whole of this big segment at its 
base. What, probably, is the use of the blade-like 
branch of the antenna just under the eye? Compare 
the antenna and its branches with a swimmeret. 

13. Above the antennae are the antennulae. Remove 
one of them and compare it with a swimmeret. 

14. In the base of each antennule, just underneath the 
eye, is the ear-sac. 

15. With the forceps pull the eye about to see its range 
of motion. Pull it out by its stalk, and examine with 
lens and microscope its black tip, or cornea. Is it 
simple or compound? 

After removing the cephalothoracic appendages, 
and the carapace, carefully clean and thoroughly 
examine the framework of the cephalothovax, still 



30 PRACTICAL ZOOLOGY. 

looking for traces of thoracic rings. The number of 
cephalothoracic segments can be determined only by 
counting the pairs of appendages. All writers are 
not agreed as to this number; some regard the eyes 
as a distinct pair of appendages, comparable to any 
pair of legs, and representing a distinct ring; but 
the eyes seem to develop from the ring which bears 
the antennulae. Again, some regard the metastomata 
as a distinct pair of appendages. The line of division 
between the head and thorax is also a matter of 
dispute. Huxley places it between the second pair 
of maxillae and the first pair of maxillipeds. Hyatt 
places the division between the first and second pairs 
of maxillae, as the space between these is membranous 
entirely across the sternal region, while back of this 
line the parts are hard and firmly soldered to- 
gether. 

The carapace is probably not a consolidation of the 
dorsal portions of all the cephalothoracic segments, 
but a backward extension of the consolidated upper 
parts of the rings of the head ; the dorsal portions of 
the thoracic rings, being thus covered, are conse- 
quently no longer developed. In certain lower 
Crustacea the carapace is unquestionably a backward 
extension of the head-shield (Hyatt). The groove 
across the carapace has been generally regarded as 
indicating the line of division between the head and 
thorax. If this line be traced its extremities will be 
found to lie between the antennae and mandibles. 
Packard states that the carapace, or shield of the 
head-thorax, niay be seen, after close examination, to 
represent the segments of the antennae and mandibles, 



THE CRAYFISH. 31 

and is so developed as to cover the other cephalotho- 
racic segments. 
16. Make, side by side, three drawings of the crayfish, — 
a dorsal, a ventral, and a lateral view, — naming all 
parts. 

CRAYFISH CARD. 

Take an entire crayfish ; separate all its parts, and paste 
them on a card, as in the case of the grasshopper ; arrange 
the eyes, antennae, antennules, mandibles, maxillae, maxilli- 
peds, and thoracic legs, symetrically about the carapace. 
Make a paper bridge on which to rest the carapace. 
Separate the rings of the abdomen, string them on the 
paper bridge, and place opposite each its appendages, 
remembering that the side parts of the tail-fin are appen- 
dages of the sixth ring. Draw in your note-book all the 
parts as arranged on the card, with the name beside each 
part. 

INTERNAL STRUCTURE OF THE CRAYFISH. 

The better dissecting pans have a thick layer of wax in 
the bottom, or a sheet of cork weighted with lead, to 
which specimens may be pinned, and dissected under 
water. Very good cheap dissecting pans may be made 
as follows : take oyster-cans that have been opened on one 
side, and cut out this side, leaving a margin half an inch 
wide. Bend this margin down inside. Cut a piece of 
shingle or cigar-box cover for a false bottom, leaving it a 
little long, so it will wedge in tightly and not float up 
when water is poured in. 

For this work use lobsters, or as large crayfishes as possi- 
ble. Place the crayfish in the dissecting pan, and cover it 



32 PRACTICAL ZOOLOGY. 

with water. Pin it to the bottom, through the telson, and 
through the big claws. Observe a groove, curving 
lengthwise, on each side of the back of the carapace. 
Insert the point of one blade of the scissors under the 
hinder edge of the carapace at one side. Cut forward, a 
little outside the above-noticed groove, to the groove 
which separates the head from the thorax. Break away 
the whole of the side of the carapace. Push the gills 
downwards, and cut them off at their point of attach- 
ment below. 

Observe the thin wall separating the cavity in which 
the gills were, the gill-chamber, from the body cavity. 
Clear away the other side likewise. With the forceps 
pick away the narrow cover of the body cavity carefully, 
as the heart lies just under the carapace. 

1. The heart is an oblong, whitish body. Look for holes 
in its upper surface, and for small white tubes running 
forward from it toward the head. With the forceps 
gently lift the hinder end of the heart; note its 
angularity. 

There are two holes in the top of the heart, two 
beneath, and one on each side. These holes are 
guarded by lip-like valves on the inside, so that when 
the heart contracts, the blood cannot flow out through 
the holes, but is driven out through the arteries to the 
various parts of the body. From the different parts 
of the body the blood goes to the gills. Returning 
from the gills, it enters the cavity in which the heart 
lies, the pericardial cavity. As the valves at the 
openings of the heart open inward, the blood readily 
flows into the heart when it expands. 



THE CEAYFISH, 33 

2. Under the heart, and projecting in front of it, are the 
reproductive organs : in the female, the yellowish 
ovaries, in which the spherical eggs may be distin- 
guished; in the male, the whitish testis occupies a 
corresponding position. The ovary on each side sends 
downward a tube, the oviduct, or egg-tube, to the 
first segment of the third thoracic leg, where it opens 
externally. The testis has a much longer, coiled 
white tube, which opens on the first segment of the 
hindmost thoracic leg. 

3. Carefully cut away the roof of the head. The space 
within the head is almost completely occupied by 
the stomach, a roundish sac, with a thin wall, in 
which is a hard framework. Gently scrape away 
the soft tissues around the stomach, and examine it 
closely. Observe the narrow gullet or esophagus 
leading from the mouth to stomach. 

4. Along the sides of the posterior end of the stomach 
and the anterior end of the intestine lie large reddish 
masses, the liver. Pick one of these masses to pieces 
to learn its structure. Find the duct leading from 
each liver into the intestine. 

5. Observe the white muscles which extend forward 
from the abdomen along each side of the body 
cavity. 

6. Beginning at the front end of the abdomen, cut with 
scissors through the roof of the abdomen to the 
telson, on each side. Seizing the fore part of this 
roof with the forceps, carefully lift it and turn it 
backward. A thin layer of white muscle may adhere 
to it, or may remain connected with the organs in 
the abdomen. This is made up of the muscles that 



34 PRACTICAL ZOOLOGY. 

straighten (extend) the abdomen. Pick it away care- 
fully with the forceps. 

7. Running lengthwise, in the middle line, is the 
intestine, a thin-walled tube, often of a dark color 
from its contents. Trace it back to the anus, and 
forward to the stomach. Carefully remove the in- 
testine. 

8. A large mass of muscle remains. This is composed 
of the muscles that bend (flex) the abdomen. Draw 
the point of a knife-blade or dissecting needle along 
the middle line of this muscle, along the bottom of 
the groove in which the intestine lay. After a thin 
layer has been cut through, the whole muscle may be 
easily separated into two rolls the whole length of 
the abdomen. Pushing these carefully aside, find in 
the middle line of the floor of the abdomen a slender 
white nerve cord, with enlargements at intervals. 
How many of these enlargements, ganglia, are there 
in the abdomen ? What relation do the ganglia have 
to the . segments ? Observe the branches, nerves, 
given off to the muscles on each side. Trace the 
nerve cord forward to the thorax, where it disap- 
pears in the hard framework of the floor of the 
thorax. Break away as much of this framework as 
is necessary to follow the cord to the head. Make 
out that the cord is double. How many ganglia are 
there in the thorax ? Note the branches extend- 
ing to the legs and other organs. From the large 
ganglion back of the gullet trace two branches for- 
ward, one on each side of the gullet, till they unite 
in a large ganglion above the gullet, thus forming 
the esophageal collar. From the ganglion above 



THE CRAYFISH. 35 

the gullet trace nerves to the eyes, antennae, and 
antennulae. 
9. Cut open the stomach, wash it out with water, and 
look on its inner walls for teeth. 

10. Study the joint in one of the big pinchers. Pick out 
the muscle from the end of the segment, and find the 
thin, tough, white tendons. Seize these with the 
forceps and pull alternately, to see how the claw is 
shut and opened. 

11. In what characters is the crayfish like the grass- 
hopper ? In what do these animals differ ? 

12. Why should the name Crustacea be applied to such 
animals as the crayfish? 

THE DEVELOPMENT OF THE CRAYFISH. 

The eggs are glued in masses to the swimmerets, under 
the abdomen of the female, and thus carried till they are 
hatched, and for some time afterward the young cling to the 
swimmerets. In its growth the crayfish sheds its crust, or 
moults, several times. In this process the carapace 
separates from the abdomen above, and cracks along the 
back. By a series of severe efforts the crayfish extricates 
itself, at first soft, defenceless, and correspondingly 
timid. Great difficulty is experienced in withdrawing the 
legs ; often they are broken off in the effort to withdraw 
them. The legs are frequently broken off at other times, 
but grow out again. 

Read "The Crayfish," Huxley; the chapter on "The 
Fresh-water Crayfish" in "Practical Biology," Huxley and 
Martin. 



36 PRACTICAL ZOOLOGY. 



THE SOW-BUG. 

Sow-bugs are usually to be found under boards and 
stones, and in other damp places. Get the largest speci- 
mens for this study. 

1. The first part is the head, or carapace. 

2. Find and describe the eyes. 

3. What are the peculiarities of the antennae ? 

4. The jaws and maxillae are closely pressed together, 
forming a short, blunt projection under the head. 
The tip of this blunt proboscis is usually black. A 
longitudinal groove shows the line of union of the 
hinder maxillse. By pinching the body of a live sow- 
bug, the mouth is sometimes more clearly shown by 
the exudation of a liquid, as in the case of a grass- 
hopper. 

Where is the line of division between the head and 
thorax? Count the appendages which may be sup- 
posed to belong to the head; how many rings do 
these indicate ? 

5. The line of division between the thorax and abdomen 
is indicated by an abrupt change in the size of the 
segments. How many segments has the thorax ? 

6. How many segments are there in the abdomen ? 

7. How manji pairs of legs are there ? How many seg- 
ments has each leg? Do the legs all extend in the 
same direction? 

8 A series of thin, over-lapping plates under the abdomen 
are the gills. In the anterior plates observe the white 
air-chambers. Beginning at the foremost of these 
gills, pick them apart with a needle. Remove them 



CYCLOPS. 37 

in this way, and with a lens make out their shape 
and arrangement. 
9. Under the thorax of the female there is a series 
of thin membranes attached near the bases of the 
legs. These are the egg-covers. The eggs, after 
being expelled from the body, undergo their develop- 
ment in the space under the thorax enclosed by these 
egg-covers. Look for specimens carrying eggs in this 
manner. 
10. In what respects are the sow-bug and crayfish alike ? 
In what respects do they differ from each other? 

The crayfish and sow-bug both belong to the 
Crustacea. The class Crustacea is divided into 
several orders. The order to which the crayfish 
belongs is the Decapoda, or ten-footed; the sow-bug 
belongs to the order Tetradecapoda, or fourteen- 
footed. 

See Chapter XVIII of Morse's "First Book of Zoology." 



CYCLOPS. 

Along the sides of aquaria, and sometimes in drink- 
ing-water, there may be seen minute white animals 
swimming with a jerky motion. Cyclops has a pear-shaped 
body, and is just large enough to be seen readily with the 
naked eye. The females carry two egg-masses attached to 
the sides of the abdomen. With a lens, watch these 
animals through the side of the aquarium. Place a female 
cyclops with a few drops of water in a watch-crystal, or 



38 PRACTICAL ZOOLOGY. 

on a piece of glass. Examine under a three-legged lens or 
under a low power of the microscope. 

1. The foremost division of the body is the carapace. 
How many segments has the thorax ? 

2. The egg-sacs are attached to the first ring of the 
abdomen. 

3. The eye ; note its color, position, shape, and parts. 

4. The antennae and other appendages. 

5. How does cyclops swim ? 

Make a careful drawing of cyclops as seen from above. 

Cyclops belongs to the order Entomostraca (water-fleas). 
Read " Anatomy and Metamorphosis of Cyclops," in 
Brooks' " Handbook of Invertebrate Zoology." 



OTHER CRUSTACEA. 

The lobster is almost exactly like a crayfish, only larger. 
If a lobster can be obtained, carefully compare it with the 
crayfish. Shrimps are also very much like crayfishes. 
Crabs have wide bodies and very short abdomens, folded 
closely under the bodj^. The structure of crabs, both 
internal and external, is essentially the same as that of 
crayfishes. The crab which is so much used for food has 
the hinder pair of legs developed as paddles for swimming, 
the outer segments being flattened. This crab swims 
sideways. Just after moulting it is known as the " soft- 
shell crab." 

The little oyster crab, which often comes to us with our 
oysters, is not a young crab, but is the female of one of 
the smaller species of crabs. 



OTHER CRUSTACEA. 39 

The hermit crab backs into the empty shell of a sea- 
snail, thus protecting the soft hinder parts of his body, 
and with his head and anterior appendages projecting, 
crawls about, dragging his house with him. When the 
hermit outgrows his shell, he exchanges it for a larger 
one. When first hatched it is like other crabs. 

The sand crab runs rapidly on the beach, and when 
pursued, and not near its hole, quickly buries itself in the 
sand, leaving only the black tips of its eyes exposed. This 
crab is nearly white. 

The fiddler crab is small. The male has one large claw, 
which it holds across the front of its body. The other 
claw is very small, the two suggesting the violin and 
bow. It lives in holes between high and low tide 
marks. The writer has seen these crabs covering the 
beach for many rods, so thickly crowded as almost to 
touch each other, making a loud rustling noise as they 
shuffled away from their uninvited visitor. 

Lobsters, crabs, and shrimps live in salt water. 

Some small crustaceans, found in ponds, swim actively 
about, enclosed in a bivalve shell, formed by the growth 
of the carapace, which they can open and shut. 

Collect a variety of the common small crustaceans, keep 
them in a fruit jar, and study their habits. 

Consult " Worms and Crustacea " in Hyatt's " Guides 
for Science Teaching," " Packard's Zoology," and Huxley's 
" Anatomy of Invertebrated Animals." 

Look over the descriptions of the crayfish and sow-bug, 
and make a list of the characters common to the two. Let 
this list represent the characters of Crustacea generally. 
Place side by side (1) the list of characters common to all 



40 PRACTICAL ZOOLOGY, 

the insects studied, (2) the characters of spiders, (3) the 
characters of myriapccls, (4) the characters of crustaceans, 
and by comparing these four lists make the following : — ■ 

1. A list of characters which they all have in common. 

2. A list of characters which insects have, but which the 
others have not. 

3. A list of characters which spiders have, but which 
the others do not have. 

4. A list of characters which myriapods have, but which 
the others do not have. 

5. A list of characters which crustaceans have, but which 
the others do not have. 

Which are more striking, the differences or the resem- 
blances, in thus comparing these four groups? 

The four classes, Insecta, Arachnida, Myriapoda, and 
Crustacea, constitute the branch of the animal kingdom 
called the Arthropoda. 

List 1 ought to be an approximate definition of the 
branch Arthropoda. 



THE EARTHWORM. 

Place a live earthworm on a newspaper on the table, 
and watch its motions. How does it crawl ? Is the same 
end always foremost ? Are the two ends alike ? Near 
the anterior end is the thick white girdle; is it a complete 
girdle ? Count the segments ; are they all alike ? Com- 
pare the upper, dorsal, surface with the under, or ventral, 
surface. A dorsal vessel can usually be seen under the 
dorsal surface ; watch for pulsations. With the forceps 



THE EARTHWORM. 41 

seize the worm near the posterior end and drag it back- 
ward ; is there resistance ? Repeat, and listen attentively. 
Lay the worm over the tip of the forefinger, and drag it 
backward and forward. Look for fine spines; how are 
they arranged, and in what direction do they point? Note 
the mouth opening at one end, and the anus at the other. 
Draw as seen from above (dorsal view). 

DISSECTION OF THE EARTHWORM. 

Use the dissecting pan as for the crayfish. Half fill the 
can with water, and renew if it becomes muddy during 
dissection. Have in readiness two dozen pins. 

Kill a large earthworm by putting it into a tumbler and 
covering it with ether or alcohol. 

1. Lay the specimen lengthwise in the middle of the dis- 
secting pan, stretch it, and pin it firmly at each end. 
With sharp, fine-pointed scissors cut through the skin 
of the back, near the posterior end, continuing the cut 
forward a little to one side of the middle line. Stretch 
the edges of the skin out to the sides, and pin down, 
slanting the pins so they will be out of the way. 

2. If a milky liquid be found, place a drop of it on a 
slide, cover it with a cover-slip, and examine with a 
high power of the microscope. White blood cor- 
puscles should be seen. 

•1. As soon as the edges of the cut are separated, the 
intestine, usually of a dark color, from its contents, 
is seen. 

4. Along the top of the intestine runs the dorsal vessel. 
This is perhaps not a true " blood-vessel," for many 
regard the milky liquid, above noted, as the real 
blood. 



42 PRACTICAL ZOOLOGY. 

5. Observe the muscular partitions between the seg- 
ments ; what is their relation to the intestine ? Care- 
fully compare the partitions with the external mark- 
ings and the sets of spines. Are there as many seg- 
ments as are indicated by the external appearance? 

6. The brownish substance along the top of the intestine 
is the liver. 

7. Continue the cut to the anterior end, being very 
careful not to cut the intestine, especially in the part 
anterior to the girdle. Pin well out. Cut the parti- 
tions down at the sides, to free the inner structures. 

8. In the region of the tenth segment are several roundish 
white bodies, — reproductive organs. 

9. Alternating with these are several red masses. These 
are side branches of the dorsal blood-vessel, which 
curve downward on each side of the gullet, to unite 
with a ventral blood-vessel, thus forming rings around 
the slender gullet. These rings have enlargements, 
thus resembling necklaces. 

10. Back of the reproductive organs are two enlargements 
of the digestive tube, different from the intestine. 
The foremost of these is the crop, the hinder is the 
gizzarck 

11. In the first six segments is a wide portion of the 
digestive tube, the pharynx. Carefully dissect away 
the thick muscular partitions, to see it more clearly. 
This pharynx is used as a proboscis, being protruded 
from the mouth and inverted. 

12. The pharynx narrows behind into the gullet. Trace 
this back under the reproductive organs to the crop. 
The gullet is the narrowest part of the digestive tube, 
and if the reproductive bodies have been sufficiently 



THE EARTHWORM. 43 

studied, they may be dissected away, to disclose the 
gullet more fully. Review now the whole digestive 
tube, pharynx, gullet, crop, gizzard, intestine. 

13. Under the intestine is a ventral vessel. Find its 
side branches. 

14. Cautiously dissect away the intestine and find under 
it a slender white thread, the nerve cord, having 
swellings, or ganglia, in each segment. Trace this 
nerve cord to its posterior end. Then trace it for- 
ward. Under the anterior part of the pharynx it 
divides, sending a branch up on each side of the 
pharynx. These branches unite in a large, double 
ganglion above the anterior end of the pharynx. 
This nerve collar is similar to that found in the 
crayfish and in insects. 

15. The thin outer skin, or cuticle, which easily peels 
off in alcoholic specimens, was probably noticed in 
cutting along the dorsal wall. Observe the pearly 
lustre of the cuticle. Under the true skin is a layer 
of muscle, with fibres running circularly. Under- 
neath this is a second layer of muscle, whose fibres 
run lengthwise. By the contraction of the circular 
fibres the segments are made narrower and longer ; 
thus the body is extended. If the spines are held 
pointing backward, the body will be pushed forward. 
When the longitudinal fibres contract, the body is 
shortened, and, owing to the direction of the spines, 
is pulled ahead. 

16. The reproductive organs are alike in all the individ- 
uals of a given species of earthworms. All lay eggs. 
There are no males, no females. They pair, each 
fertilizing the eggs of the other. Animals of this 



44 PRACTICAL ZOOLOGY, 

kind, in which the sexes are united in the same 
individual, are called hermaphrodites. 

17. There are no lungs, no gills. Oxygen is taken by the 
blood as it circulates, through the skin. 

18. There are no eyes, but the first two segments seem to 
be sensitive to light. 

19. The worm, in digging a new hole, or deepening an old 
one, swallows the soil, and passes it through its 
intestine, the partly decayed vegetable matter in the 
soil furnishing nourishment to the worm. The coiled 
castings at the tops of the holes have probably been 
noticed by all. In damp weather the worms come to 
the surface to draw leaves, twigs, and seedling plants 
into their holes. These holes are sometimes six feet 
deep. It is found that the leaf is rolled together and 
drawn into the hole with the stem pointing up. 
Taken an inch or two below the surface, the leaves 
soon become softened, and in a partly decayed condi- 
tion are eaten. In this way, without the aid of teeth 
or hard jaws, the worm obtains food solely by the 
suctorial power of its proboscis. 

20. Make a drawing showing the whole digestive canal as 
seen from above. Draw a cross-section of the body 
(i.e., what is seen if the body is cut across), and a 
vertical longitudinal median section (as seen by 
splitting lengthwise, from top to bottom, in the middle 
line). 

RANK OF EARTHWORMS AMONG ANIMALS. 

Animals are ranked according to the number of things 
they can do, and do well. The earthworm has many 
parts, but they are all nearly alike, and do not enable it to 



THE EARTHWORM. 45 

do many different things. A part of an animal having a 
special work to do is called an organ, and its work is its 
function- The earthworm has many organs, but few 
functions. Apply this principle to man and an ape. Each 
has four limbs. The ape is called four-handed, but has no 
good hands ; he cannot handle things well. He has not 
good feet ; he cannot walk well. What is the one thing he 
can do well with his four foot-hands? How many distinct 
functions has man with his hands and feet ? Multiplica- 
tion of parts without corresponding variety of structure 
and function mark an animal as low in rank. 

Another respect in which the earthworm is low is this, — 
the head end is not much better than the tail end. There 
is no distinct head. At first glance there is not much 
difference. Many worms similar to the earthworm can be 
cut in two, and each part lives ; the hind part developing a 
new head, and the fore part a new tail. The part of the 
nervous system in the head is not greatly different from 
other parts. Just in proportion as the head rises in 
importance, and the whole set of organs centre around it, 
the animal rises in the scale. Apply this test to the earth- 
worm and crayfish, crayfish and crab, bee and dragon-fly. 

Compare insects with earthworms in rank from another 
point of view. Most insects, before reaching the adult 
state, pass through a worm-like stage. Crabs are at first 
like crayfishes in having a well developed abdomen. As the 
crab grows, the abdomen shortens, and the head becomes 
more prominent. What would this indicate as to the 
relative rank of worms and insects? of crayfishes and 
crabs? Worms constitute one branch of the animal 
kingdom. In this branch, Vermes, are the leech, trichina, 
tapeworm, with many animals very unlike the earthworm 



46 PRACTICAL ZOOLOGY. 

in appearance. In classifying animals, the more significant 
characters are internal structure and mode of development 
rather than mere outer form and general appearance. Most 
worms have gills. Worms never have jointed appendages. 

There is a group of slender worms called hair-worms. 
" They sometimes occur in horse-troughs, whence they are 
supposed by the ignorant to be transformed horse-hairs." 

In what characters are worms like Arthropods ? How 
do worms differ from Arthropods ? 

Read the life history of the tapeworm and the trichina. 

Read Darwin's " Vegetable Mould and Earthworms," 
the description of the earthworm in Huxley's " Anatomy 
of Invertebrated Animals," "Anatomy of the Earthworm" 
in Brooks' " Handbook of Invertebrate Zoology," " Worms 
and Crustacea," No. VII in Hyatt's " Guides for Science 
Teaching." 



THE FRESH-WATER CLAM. 

STUDY OF THE LIVE CLAM. 

Look for fresh-water clams in the sandy bottoms of creeks 
and rivers. They may be found nearly buried in the sand or 
mud. If no better aquarium be at hand, take an old tub, 
half fill it with water, and have two or three inches of 
sand at the bottom. Drop several clams into the water, 
and note carefully the place and position of each. On the 
next day see if any of them have changed either place or 
position. The part uppermost, in the natural position, is 
the back. Look near one end, where the shell opens a 
little, for two oval holes. These are the siphons; gently 



THE FBESH-WATEE, CLAM. 47 

touch the margin of one of them. What follows? The 
water enters one of these openings and comes out of the 
other. Prove the action of each by stirring up a little 
mud, to show the currents ; or take a small glass tube, dip 
the lower end into ink, or finely divided indigo in water, 
then placing a finger over the upper end of the tube, lift 
out a little of the ink. Keeping the finger tightly on the 
top of the tube, thrust the other end down to a point 
just above the siphonal openings ; then raise the finger 
and release some of the ink. In some way prove the exist- 
ence of these currents. Let each pupil have a clam in 
a fruit-jar, with sand enough to support the clam. Keep 
the clams alive for a week or more, and watch them daily. 

THE CLAM-SHELL. 

If a live clam is used, place it on a plate, or in the 
oyster-can. 

1. Notice the two parts of the shell, — the valves. 

2. The edge along which the shell opens is the ventral 
margin. 

3. The edge by which the two valves join each other is 
the dorsal margin, or hinge margin. 

4. The concentric lines parallel to the ventral margin 
are the lines of growth. 

5. The raised point around which these lines centre is 
the beak, or umbo. 

6. The umbones are nearer the front, or anterior, end of 
the clam. 

7. Toward the posterior end, back of the umbones, 
between the valves, and uniting them, is the hinge- 
ligament. 



48 PRACTICAL ZOOLOGY. 

8. Hold the closed shell with the umbones and hinge- 
ligament uppermost, the latter nearer, and the former 
pointing away from you. 

The end pointing from you is the anterior end. 

The end pointing toward you is the posterior end. 

The upper edge is the dorsal margin. 

The lower edge is the ventral margin. 

The half shell to your right is the right valve. 

The half shell to your left is the left valve. 

Fix these relations firmly in mind. 

9. Make a drawing of the clam as seen from one side, 
naming all the parts. 

10. Draw as seen from above, placing this drawing along- 
side the side view. 

11. Draw the clam as seen from the anterior end. 

12. Observe the color, the degree of cleanness, and 
general condition of the different parts of the shell, 
and consider the relations between these facts and the 
position of the clam when first found. 

DISSECTION OF THE CLAM. 

Put the live clam for a few minutes into water as warm 
as the hand can well bear. This causes the muscles to 
relax, so that the shell can be readily opened. If warm 
water cannot be easily obtained, the clam may be opened 
with a strong knife, after reading the directions which 
follow. 

Pry apart the two valves, and insert a small block to 
keep them from shutting. 

1. Observe a soft white membrane, the mantle, adhering 
to the inner surface of the shell. Now hold the clam 



THE FRESH- WATER CLAM. 49 

in the left hand, with the hinge-margin resting in 
the palm of the hand, and the anterior end toward 
you. Insert the blade of a knife between the mantle 
and the upper (left, if held as directed) valve, and 
gently separate them by sliding the blade of the 
knife along the inner surface of the shell. In this 
way proceed backward, around the posterior end of 
the shell, then forward along the dorsal margin. 
Back of and below the hinge is a large white muscle, 
which extends directly across from valve to valve. 
Cut this off close to the left valve. In like manner 
loosen the mantle at the anterior end, and find 
another muscle connecting the two valves near the 
anterior dorsal margin. Sever as before, close to the 
left valve, and loosen the mantle completely from the 
upper valve, and turn this valve back like the lid of 
a box. What makes the valve spring up after the 
muscles are severed ? 
2. Lay the clam in a deep plate, or in the oyster-can, 
and cover it with water. Renew the water as often 
as it becomes turbid. 

Observe that the left mantle lobe now covers the 
body, and that the right lobe lines the right valve. 
Notice the thicker margin of the mantle. Pinch this 
thick edge ; what follows ? Observe a thin, dark- 
colored membrane bordering the edge of the shell. 
This is an extension of the outer covering, or epider- 
mis, of the shell. Scrape off some of the epidermis 
to see its relation to the limy shell. Carefully study 
the relations of the epidermis to the mantle. Turn- 
ing to the uninjured mantle lobe, pinch the edge of 
the mantle, and observe the effect on this free border 



50 PRACTICAL ZOOLOGY. 

of the epidermis. Trace the right and left mantle 
lobes to their points of union before and behind. 

3. Examine the thick, dark-colored, hinder edge of the 
mantle lobes, and see how by their manner of meeting 
they form the two short tubes, the siphons, seen in 
the live clam ; prove the great sensitiveness of the 
margins of these siphon tubes. Are the margins of 
the two openings alike ? 

4. Examine the ends of the anterior and posterior ad- 
ductor muscles where they were cut off in opening 
the shell ; scrape away any part of these muscles that 
may remain attached to the left valve, and note the 
marks or muscle scars which are shown. 

5. Turn the mantle lobe back as far as it will go, and 
observe the soft abdomen; its tough lower border is 
the foot j prick it with the dissecting needle, and ob- 

' serve what follows. 

6. Along each side of the abdomen and extending back 
of it are two thin membranes, the gills, showing ver- 
tical parallel markings (sometimes the outer gill is 
thick, and of a dark color) ; study closely the rela- 
tions of the gills to each other, to the body, and to 
the mantle. With a knife scrape off a little of the 
surface of the gill and examine under the microscope 
to see the vibratory motion of the hair-like projec- 
tions, or cilia, borne on the cells thus obtained. 

7. In front of the gills, on each side of the body, are two 
thin, triangular flaps, much smaller than the gills, the 
labial palpi. 

8. Raise the hind border of the left mantle lobe, and 
observe that the gill next to the body unites with the 
corresponding gill of the other side, thus forming a 



THE FKESH-WATER CLAM. 51 

separate channel above the gills, into which the 
upper siphon leads, while the lower siphon leads to 
the lower cavity, outside of and below the gills. 
9. With the thumb and all the fingers of the left hand 
seize the left lobe of the mantle and pull it toward 
the ventral margin, thus drawing the body away from 
the dorsal margin. Just under the hinge a pale organ 
may be seen, pulsating every few seconds ; this is the 
heart, 
10. Holding the mantle stretched, again examine the 
upper siphonal opening ; probe to see how it extends 
forward above the united hinder portion of the gills. 
In the upper part of this cavity find a tube running 
back over the posterior adductor muscle, and ending 
in a conical elevation ; this tube is the intestine, and 
the opening at its end is the anus; hence the siphon 
leading from this cavity is called the anal siphon; the 
lower siphon, which conducts water to the gills and 
mouth, is called the branchial siphon or gill siphon. 
Examine the gills from above, i.e., examine their 
dorsal margins; observe that the two outer walls of 
each gill are a short distance apart at this edge, while 
below these walls unite, so that if the gill be cut 
across, these walls, as seen at the cut, are like the 
letter V. These diverging walls are connected by 
cross partitions, thus forming a series of compart- 
ments within the gill, whereas if these partitions 
were absent, each gill would be a deep, narrow r , undi- 
vided trough. The lateral walls of the gills are sieve- 
like, and the surface of the gill and the edges of the 
holes are covered with cilia. The vibrations of these 
cilia drive the water which is around the gill through 



52 PRACTICAL ZOOLOGY. 

these holes into the cavities within the gill; the 
water from each compartment of the gill passes up 
into the chamber leading to the anal siphon. 

Beginning at the upper edge of the anal siphon, in 
the middle line, cut carefully forward just above the 
intestine as far as the umbo. This lays bare the cav- 
ity in which the heart lies, the pericardial cavity. 
Carefully cut away the thin covering of this cavity 
and make out the following parts : — 

a. The large yellowish ventricle in the anterior part 
of the cavity; time its pulsations; observe that 
the intestine runs directly through the ventricle, 
though it has no more communication with the 
ventricle than a stove pipe has with a room it 
passes through; an artery runs forward from, the 
ventricle along the upper surface of the intestine; 
another artery runs from the ventricle backward 
under the intestine. Again pull the mantle ven- 
tral-ward to show b. 

b. A thin sac, triangular as seen from the side, with 
its apex joining the ventricle, and its base 
attached just above the upper edge of the gills ; 
this is the left auricle. Each auricle receives 
the blood from the gills of the corresponding side. 

11. Just in front of the posterior adductor muscle is the 
dark kidney. 

12. Above the kidney, and in front of the posterior 
adductor, is a small muscle, which extends backward 
from the side of the body to join the valve near the 
posterior adductor. This muscle pulls the foot back- 
ward. 



THE FKESH-WATER CLAM. 53 

Look near the anterior adductor for similar mus- 
cles ; what work do they perform ? 

13. To find the mouth, hold the clam, anterior end upper- 
most, still attached to the right valve, in the left 
hand ; press down the point of the foot, and find the 
mouth opening below the anterior adductor ; observe 
that the two outer palpi unite above the mouth, and 
the two inner palpi unite below the mouth. Back of 
the anterior adductor a dark-colored mass may be 
seen within the body; this is the liver, which sur- 
rounds the stomach ; the intestine has several coils in 
the body before emerging on the dorsal surface a 
short distance in front of the heart. The intestine 
can be traced much better in an alcoholic specimen. 

14. Beginning at the posterior adductor, cut away all the 
free flap of the left mantle lobe, following the upper 
edge of the gills (being careful not to cut away the 
labial palpi) to the upper edge of the anterior ad- 
ductor. Make a drawing of all the parts above 
named, as they lie in the right valve. 

15. Remove the remaining soft parts in as good condition 
as possible, and put into alcohol, for the dissection of 
the nervous system. 

16. Make a drawing of the inside of one of the valves, 
showing the hinge, the muscle scars, and any other 
markings that have any significance. Sometimes 
there can be distinctly seen a line running near, and 
parallel to, the ventral margin, along which the upper 
edge of the thicker portion of the mantle was at- 
tached; this is the mantle line, or pallial line. 

17. Some clams have hinge teeth, by which the dorsal 
edges of the valves are more firmly held together 



54 PRACTICAL ZOOLOGY. 

when the shell is shut. The irregularly shaped teeth 
near the umbones are the anterior, or cardinal teeth; 
back of these are the long, narrow posterior, or 
lateral teeth. 

18. Take an empty shell with the valves still hinged 
together ; cut and fit into this shell a piece of paper 
showing the shape of the whole mantle. Make also a 
plaster of Paris cast of the inside of the shell. 

19. Wipe dry a number of shells and weigh them. After 
thoroughly roasting them in a fire, weigh them again. 
If the shells are not burnt too long, some of the 
animal matter may remain in the form of layers of 
charcoal between the layers of lime. 

20. Put a shell into dilute acid to dissolve out the lime. 
Observe the animal matter remaining undissolved. 
Compare the effect of acid on equal pieces of burnt 
and unburnt shell. 

21. Carefully pick to pieces a burnt shell and distinguish 
an inner and an outer portion of the shell, the line of 
division between which appears on the inner surface 
of the shell along the mantle line. Make out the 
successive layers of the outer part which were built 
by the outer part of the mantle, and the layers formed 
by the thinner, inner part of the mantle. 

22. Break a burnt shell across from the umbo to the 
ventral margin, and make a drawing of the edge thus 
exposed, showing the arrangement of these sets of 
layers. File a groove from the umbo to the ventral 
margin of afresh shell, and break it across. Compare 
the edges of this with the corresponding part of the 
burnt shell. 



THE FRESH-WATEK CLAM. 00 

THE NERVOUS SYSTEM OF THE CLAM. 

This dissection requires the utmost care and patience. 
Take a clam that has been hardened in alcohol, or by 
boiling. Dissect under water; rinse the specimen often. 

1. Immediately under the posterior adductor muscle 
find a double, yellowish body ; this is composed of 
the two parieto-splanchnic ganglia; dissect away 
the thin membrane covering them. 

2. From these ganglia trace nerves backward to the 
gills and to the posterior borders of the mantle 
lobes; trace also two nerves forward, carefully dis- 
secting away the soft parts that cover them ante- 
riorly, and trace them to the sides of the mouth 
where they join 3. 

3. The cerebral ganglia: these lie near the surface at 
the bases of the labial palpi. Trace a small nerve 
which connects the two cerebral ganglia over the 
mouth. 

4. From each cerebral ganglion trace nerves backward 
and downward to 5. 

5. A pair of orange-colored pedal ganglia, lying to- 
gether deeply imbedded between the foot and the 
abdomen. 

In the alcoholic specimen the stomach and intestine 
may be traced. Cross-sections of alcoholic specimens 
may be made with a razor, which show admirably the 
relations of the different parts of the clam. 

THE DEVELOPMENT OF THE CLAM. 

If the outer gills be thick and dark-colored, open one 
of them, remove some of its contents, and mix with water 



56 PRACTICAL ZOOLOGY. 

in a watch-crystal or on a slide. Examine with a one- 
inch objective or a lens. Make a drawing of the young 
clams. Compare the shapes of the young and adult. 
Watch carefully for movements of the young clams. 

The shell grows by additions deposited by the mantle 
on the inner surface of the valves. Each new layer 
projects beyond the others; so the shell grows in width 
as well as thickness. Where is the thickest part of the 
shell? If a thin piece of glass is slipped between the 
mantle and its corresponding valve, and the clam be kept 
alive, the shell substance is deposited over the glass, and 
the glass becomes buried in the nacreous matter of the 
internal layer. Grains of sand become pearls by the 
secretion of similar nacre around them. 

Read "The Fresh-water Mussel" in Huxley and Mar- 
tin's " Practical Biology "; " The General Anatomy of a 
Lamellibranch " in Brooks' "Handbook of Invertebrate 
Zoology " ; No. VI of Hyatt's " Guides for Science Teach- 
ing"; Packard's " Zoology." 



THE SNAIL. 

A dipper with a perforated bottom, attached to a 
wooden handle, will be found convenient in scooping 
up the sand and mud from the bottoms of ditches and 
streams ; the dirt being sifted out, the shells and other 
objects will be left behind. Get a number of live snails, 
and keep them in a fruit-jar. 

1. The broad disk on which the snail creeps is the 
foot. 



THE SNAIL. 57 

2. The "horns" are the feelers, or tentacles; touch 
them ; what would seem to be their use ? 

3. The dark spots at the bases of the tentacles are the 
eyes; are they borne on a stalk in any common 
snails ? 

4. Watch the snail crawling on the glass ; near the front 
of the foot the mouth may be seen; observe its open- 
ing and shutting as the snail gathers food from the 
surface of the glass. Do snails clean the glass or 
foul it ? 

Most snails have a ribbon-like tongue, fastened at 
each end, and covered with teeth; as this tongue is 
applied to an object, and drawn rapidly back and 
forth, it acts like a rasp ; in this way some marine 
snails bore holes through the shells of other mollusks 
and feed on them. 

5. Many snails have gills ; others breathe by a simple 
lung. Watch the snails, to see if any of them come 
to the surface to get air ; how is this done ? 

THE SNAIL-SHELL. 

1. The pointed end is the apex. 

2. The opening at the large end is the aperture. 

3. The outer edge of the aperture is the lip. 

-i. The lines parallel to the lip are the lines of growth. 

5. The spiral groove on the outside is the suture. 

6. The turns of the shell between the groove are the 
whorls. 

7. The whorls, taken together, make the spire. 

8. The lid closing the aperture is the operculum; is (his 
present in all the snails you find? 



58 PRACTICAL ZOOLOGY. 

Make a drawing, naming all the parts, of the snail-shell 
with the aperture toward you ; with the aperture away 
from you; with the apex toward yon. 

Lay the snail-shell beside a common screw; if the 
whorls turn like the threads of the screw, it is a right- 
hand shell; if they turn the other way, it is a left-hand 
shell; the right-hand shells are sometimes called dextral, 
and the left-hand, sinistral. 

Clams, snails, and oysters belong to the branch of the 
animal kingdom called Mollusca; the clam is a bivalve; 
the snail is a univalve. 

Read Morse's " First Book of Zoology,' 9 on snails and 
clams. 



PARAMGECIUM. 

In a tub, or aquarium, in which clams have been kept, 
a thin white film may form on the surface of the water. 
This is more likely to occur if some of the clams die and 
the water gets " bad." Place on a slide a drop of this 
water with some of the white film, with a piece of paper 
under the edge of the cover to keep from crushing the 
animalcules. Examine first with a low, then with a high 
power of the microscope. 

Paramoecium is somewhat slipper-shaped, swimming 
actively by means of vibrating, hair-like projections, or 
cilia; are these of the same size on all parts of the body? 

Find, on one side of the body, a widely open, funnel- 
shaped cavity, extending obliquely backward into the 
body; this is the vestibule; the narrower, inner part of 
this funnel-shaped cavity is the gullet, or esophagus; 



PAKAMCECIUM, 59 

observe that this whole cavity is lined with cilia, and that 
they are in active operation, producing currents in the 
water, by which food-particles are swept into the mouth ; 
the gullet does not lead by a continuous tube to a defi- 
nite stomach, but any part of the body within acts as a 
stomach. When a collection of food-particles has accu- 
mulated at the lower end of the gullet, the mass, by a 
contraction of the body, is forced further into the soft 
substance of the body, leaving the blind end of the gullet 
as it was before. By sifting some finely powdered indigo 
into the water this process of taking food may be better 
seen. These animals seem to have little or no sense of 
taste, as indigestible particles are readily taken in. There 
is a regular place for ejecting such indigestible matter; 
watch patiently to make out where this is. 

Note the changes of shape which the body undergoes 
as it forces its way through narrow places, between par- 
ticles of sediment in the water. 

If a specimen that is pretty quiet be carefully watched, 
a large transparent space will be seen at some point in the 
body; this, after remaining visible for some twenty or thirty 
seconds, will suddenly disappear, and gradually reappear ; 
this is the contractile vesicle. In some species there are 
two contractile vesicles. 

Watch closely the food-masses ; do they retain their 
original size? Do they maintain a fixed position? 

Make a drawing showing — 

1. The shape of the body. 

2. The vestibule and gullet. 

3. The food-masses. 

4. The cilia. 

5. The contractile vesicle. 



60 PEACTICAL ZOOLOGY. 

In swimming, is the same end always foremost? 
Read " The Structure of Paramcecium " in Brooks' 
" Handbook of Invertebrate Zoology." 



THE BELL-ANIMALCULE (VORTICELLA). 

Collect leaves and grasses that have fallen into water, 
and the stems and leaves of water plants from ponds and 
ditches ; place some of these leaves in a plate of water, 
and examine them closely; with the naked eye there 
may sometimes be seen on them little patches resembling 
mould ; when observed more closely these appear to be in 
the form of minute tufts , if these tufts shrink back when 
touched, take a lens and examine carefully ; cut out a part 
of a leaf bearing these clusters, put on a slide with a drop 
of water, cover with a cover-glass, and examine with a 
one-inch objective. 

Sometimes these tufts, which are colonies of Vorticellae, 
may be attached to the sides of an aquarium, or jar, in 
which clams have been kept. 

Some kinds of Vorticellse are not in colonies, but are 
borne singly on independent stalks. 

When one is found, note, using a one-inch objective: — 

1. The bell-shaped body. 

2. The contractile stalk ; suddenly jar the table, or 
stage of the microscope, by tapping with a hard 
object ; what follows ? 

Put on a high power objective and make out the follow- 
ing parts of the body : — 



THE BELL-AiSIMALCULE. 61 

1. The projecting outer rim is the peristome. 

2. The central disk, projecting above the peristome. 

3. The short, hair-like cilia on the border of the disk 
and peristome ; watch the motion of these cilia, and 
the currents of water thus produced. 

4. A depression between the peristome and disk, deep- 
ening at one place to make the vestibule, or entrance 
to the gullet, which extends a short way into the 
body. 

5. A clear space, just under the disk, is the contractile 
vesicle; watch this closely for some time; what 
changes occur? 

6. At various points in the body may be seen rounded 
masses, the food-balls; do they remain of the same 
size, and keep the same place ? 

7. Make drawings showing the above points. 

Watch patiently to see the accumulation of particles at 
the lower end of the gullet; after a time this mass may 
be seen to be pushed into the body. This forms one of 
the food-balls. These food-balls may be seen moving on 
in a circle within the body. Ejection of undigested mat- 
ter takes place near the mouth. Sometimes two vorti- 
cella are found on one stalk ; by watching it patiently it 
may be found that the vorticella is dividing to form two 
vorticellse ; this is one way these animals have of repro- 
ducing. What powers and faculties have you and the 
vorticella in common ? 

Read " The Structure of Vorticella " in Brooks' " Hand- 
book of Invertebrate Zoology." 



62 PRACTICAL ZOOLOGY. 



AMCEBA. 



One of the simplest forms of animal life is Amoeba, It 
is found in standing water, where it lives on the leaves of 
submerged plants or in the mud and ooze at the bottom. 

Scrape up a thin layer of the ooze and allow it to stand 
a few days. 

Place a drop of such water, with a little of the sedi- 
ment, on a clean slide, and cover with a clean cover-slip; 
if there be no solid matter in the drop of water, lay a 
strip of paper on the slide before putting on the cover- 
slip, letting one edge of the cover rest on it. Examine 
with a high-power objective. 

The amoeba is like a minute drop of jelly, pale (nearly 
colorless), with a more dotted central portion. Its most 
noticeable characteristic is its slow, peculiar mode of 
changing its form. 

The following parts of the body should be made out : — 

1. A clearer outer margin. 

2. A dotted or granular inner portion. 

3. A clearer, round body, in the granular part, called the 
nucleus. 

Study carefully the movements of the amoeba ; first a 
part of the clear outer portion bulges out, or is sometimes 
thrown out as a long projection, called a pseudopodium ; 
then the granular part flows into this, and by repeating 
this process the amoeba creeps along with a slow gliding 
motion, though sometimes the pseudopodia are thrust out 
and retracted without moving the body as a whole ; care- 
fully watch the beginning and the whole process of form- 
ing a pseudopodium ; look for movements of the granules 
in the central portion. 



AMCEBA. 63 

The larger granules within are particles of matter that 
have been taken in as food through that part of the body 
with which they first came in contact; there is no mouth, 
no stomach, but any place on the surface serves as a mouth 
when a mouth is needed, and any place within serves as a 
stomach when food is thus taken ; neither is there a defi- 
nite opening for ejecting indigestible matter, but by flow- 
ing around the substances it meets, it in a way swallows 
them, and, having digested and absorbed such parts as are 
suitable for food, ejects, or rather flows away from the use- 
less remnants. 

Make a series of sketches of the outline, at as short 
intervals as possible, to show the changes of form. 

Make also a careful drawing, showing all the parts of 
the body that have been made out. 

The jelly-like substance of which the body of the amoeba 
is composed is protoplasm. 

The amoeba reproduces its kind by simply dividing into 
two parts, each of which becomes a perfect amoeba. 

"Thus the amoeba lives, moves, eats, grows, reproduces 
its kind, and after a time dies, having been during its 
whole life hardly anything more than a minute lump of 
protoplasm." 

The simplicity of the structure of the amoeba and its 
simple mode of reproduction show its low place in the 
animal kingdom; with the Vorticella, Paramoecium, and 
myriads of other microscopic aquatic animals, the Amoeba 
represents the lowest branch of the animal kingdom, the 
Protozoa. Most of the Protozoa are one-celled animals, 
in distinction from some of the higher protozoa, which 
some authors regard as many-celled, and all other animals 
from sponges to man, which are undoubtedly many-celled. 



64 PRACTICAL ZOOLOGY. 

Thus the simpler Protozoa correspond to the eggs of the 
higher animals, or the cells of which their bodies are 
composed. 

Many of the protozoans have no hard parts, others have 
shells ; chalk is composed of the shells of certain marine 
protozoans, a cubic inch of chalk containing as many as 
1,000,000 of these skeletons. 

"Amoebae absorb oxygen and give out carbon dioxide and 
water, and the presence of free oxygen is necessary to their 
existence. When the medium in which they live is cooled 
down to the freezing-point, their movements are arrested, 
but they recover when the temperature is raised. At a 
temperature of 95° F. their movements are arrested, and 
they pass into a condition of "heat-stiffening," from which 
they recover if that temperature is not continued too long; 
at about 110° F. they are killed. 

"Electric shocks of moderate strength cause amoebae to 
assume a spherical form, but they recover after a while ; 
strong shocks kill them. 

"The amoeba is an animal, not because of its contractil- 
ity or power of locomotion, but because it never becomes 
enclosed in a cellulose sac, and because it is devoid of the 
power of manufacturing protein from bodies of a compara- 
tively simple chemical composition. The amoeba has to 
obtain its protein ready made, in which respect it resem- 
bles all true animals, and therefore is, like them, in the 
long run, dependent for its existence upon some form or 
other of vegetable life." 

Since the amoeba resembles one of the cells of the 
higher animals, it is important to fix in mind these 
properties and modes of life which are common both to 
amoebae and the cells of the higher animals, as thus we 



AMOEBA. 65 

have an explanation of many points in the physiology of 
man: — 

1. The amoeba moves ; it has the power of contraction or 
contractility, by means of which it accomplishes 
motion and locomotion. 

2. It feels ; when any disturbance, such as contact with 
a foreign body, is brought to bear on an amoeba at 
rest, it moves ; this is not because it is pushed or 
pulled, but is due to its own activity, the contraction 
of its protoplasm. Any living matter which, when 
acted on by a stimulus, is excited to activity, is said 
to be irritable (sensitive) in the sense of "susceptible 
to impression from without." 

3. But the amoeba does not always wait to be thus stim- 
ulated by something external; it moves u of its own 
accord," as we would say ; such action is called auto- 
matic; the amoeba is an individual capable of spon- 
taneous and independent activity. 

4. The protoplasm of which the body of the amoeba is 
composed is constantly undergoing chemical change; 
this change is of two kinds: one a wearing out, de- 
pending on the degree of activity, the other a building 
up, to make good the loss. The food is changed so 
that it is ready to become part of the body ; this 
process fo digestion. The building of this material 
into the body is known by the name assimilation. 
The waste products resulting from the breaking up of 
the old protoplasm are called excretions, and are 
thrown off into the same surrounding medium from 
which food is taken. All these processes of taking 
food, digesting and assimilating it, the decomposition 



(36 PRACTICAL ZOOLOGY. 

of the body as an accompaniment of activity, and the 
throwing off of the waste products, are included 
under the term nutrition. 

5. The amoeba breathes ; that is, takes in oxygen and 
throws off carbon dioxide ; this is really a part of 
the process of nutrition, being most intimately con- 
nected with the breaking down of the protoplasm 
(which invariably accompanies any form of action), 
during which not only motion, but also heat is 
produced. 

6. The amoeba reproduces its kind by simple division 
into two. Each individual of the higher, many-celled 
animals develops from an egg, which is a cell, and is 
essentially like an amoeba. As it develops, this cell 
divides, forming two ; each of these divides, and the 
division continues till many cells are formed; these 
cells are at first all alike, but soon they grow different 
from one another, and are arranged in order, forming 
the various parts of the body ; thus one set of cells 
form muscle, another set, developing in a different 
way, produce the brain and nerves; other groups of 
cells form bone, skin, cartilage, etc. Each of these 
sets of different kinds of cells is called a tissue; thus 
there is muscular tissue, nervous tissue, etc. The 
process of " growing unlike " or " growing different," 
which the cells undergo in their development, is called 
differentiation ; thus, of the cells which were all es- 
sentially alike, those of one set have taken one shape, 
and have acquired certain peculiarities by which they 
may be recognized, and we say they have become 
differentiated into nervous tissue or muscular tissue, 
etc. 



AMCEBA. 67 

Now, in the development of higher animals, while all the 
cells which result from the original cell (egg) are at first 
essentially alike, not only in structure but in properties, 
they grow unlike in this latter respect as well ; that is, 
while all the cells have at first in equal measure the proper- 
ties of motion, sensation, digestion, respiration, assimi- 
lation, and reproduction, each set (tissue) soon develops 
in a special degree some one of these properties. Take, for 
instance, the nervous tissue ; the cells composing this tissue 
are regarded as having had originally not only irritability 
but contractility, and all the other characters enumerated 
above in describing the amoeba ; but this kind of tissue has 
developed, in a high degree, the property of irritability, and 
has lost, in a large measure, the other properties ; so the 
muscular tissue, while it has not wholly lost its irritability, 
has it feebly developed when compared with nervous tissue, 
but has the power of contraction in a very high degree. 
Thus each tissue has some one of the general properties in 
a very marked degree, while the other properties are less 
apparent, though seldom entirely wanting. All the tissues 
work together for the common good of the whole animal; 
all the tissues grow by the increase of the number of their 
cells, and this is accomplished by the division of the cells ; 
but that division of cells which gives rise to new individ- 
uals is limited to the reproductive tissues. 

Although one set of tissues (the organs of digestion) 
lias the chief work of preparing the food to be built into 
the tissues of the body, yet each cell must take for itself 
the food thus prepared for it, and, really, each cell leads an 
independent life bathed in the liquid part of the blood, 
which soaks through the walls of the blood-vessels and 
surrounds every cell; from this liquid nourishment is 



68 PRACTICAL ZOOLOGY. 

taken (or cell starvation follows), and into this surround- 
ing liquid the cell throws its waste products. 

In consequence of the complexity of structure, a compli- 
cated set of organs is required to circulate this liquid to 
all parts of the body, so that each cell may be supplied, 
and to bring air into contact with this current in one part 
of its course, where oxygen is absorbed for all the cells. 

It now becomes evident why one can hold his breath 
longer after taking several deep breaths, and why distress 
for breath continues for some time after one has stopped 
at the end of a foot-race. 

The differentiation of cells in the formation of the vari- 
ous tissues of the body may be compared with the division 
of labor in a community. In a community of savages 
there is little division of labor ; each one, or at least each 
family, gets and prepares his own food, makes his own 
clothing, builds his own dwelling (if he has one), and in 
general supplies all his own wants ; in rude communities 
of more enlightened people the same is very nearly the 
case. But as time goes on, it is found more advantageous 
to divide the labor, each devoting himself to one special 
kind of work ; thus each acquires skill in his special line, 
better articles are produced, and time is saved for all; so, 
in time, come tailors and butchers, teachers and tanners. 

But just in proportion as each individual devotes him- 
self exclusively to one pursuit, he neglects the others, and 
consequently grows unable to do well in them ; that is, by 
becoming especially fit for one kind of labor, he propor- 
tionally unfits himself for others. The grocer does not 
make his own boots, clothes, hat, house, nor wagon. 

In the human body, also, the work is better done by 
having a special set of cells devoted to a given kind of 



THE WHEEL- ANIMALCULE. 69 

work ; and the cells of the different tissues, like the indi- 
vidual members of society, by giving themselves entirely 
to one kind of work, make themselves specially fit for this 
work, and become almost completely unfitted for anything 
else. 

This is what is meant by the physiological division of 
labor. 

Eead the descriptions of Amoeba in Brooks' " Handbook 
of Invertebrate Zoology," and in "Practical Biology," by 
Huxley and Martin ; the characters of Protozoa, in Pack- 
ard's " Zoology " ; the lecture " On a Piece of Chalk," in 
Huxley's " Lay Sermons, Addresses, and Reviews " ; the 
Introduction to Foster's " Physiology." 



THE WHEEL-ANIMALCULE (ROTIFER). 

Rotifers are often found in the water of an aquarium 
where clams and crayfishes have been kept ; pick out 
clusters of plant growth, found in the rubbish and sedi- 
ment in the aquarium, or on the shells of clams ; with a 
lens look at the walls of the aquarium for small, white, 
worm-like forms. 

The body of the wheel-animalcule is tapering, ending 
in a two-forked foot. At the larger end, when expanded, 
are two circular disks, fringed with cilia; the disks are 
retractile, as in Vorticella. Between the disks is the 
mouth; this opens into the pharynx, lined with teeth; 
back of the pharynx are the stomach and intestine. 

Rotifers are classed with the worms ; though small, the 
presence of a distinct digestive tube, a distinct nervous 



70 PRACTICAL ZOOLOGY, 

system, and organs of sight and hearing, show the rotifer 
to be much more highly developed than the protozoans. 

Rotifers have been dried and kept for years, and yet 
when put into water they revived. 

Study carefully — 

1. The mode of locomotion. 

2. The action of the disks and cilia. 

3. The motions of the pharynx. 

4. The contraction and expansion of the body as a 
whole. 

Make drawings showing the body both in the expanded 
and in the contracted state. 

Read the " General Characters of Rotifers" in Packard's 
" Zoology " ; " Rotifera " in Claus and Sedgwick's " Text- 
Book of Zoology." 



THE FISH. 

Let each pupil have a live minnow in a fruit-jar. 
Watch the movements of the mouth and gill-covers at the 
sides of the head. Observe the motions of the eyes. Can 
a fish wink? Does a fish sleep? Study the action of 
each fin, trying to discover what work is done by each. 
What is the chief propelling power ? Consider the fitness 
of the shape of the body for locomotion in water. 

THE EXTERNAL FEATURES OF THE FISH. 

For this work, and the dissection which follows, the 
perch is preferable, but bass or croppies serve very well. 



THE FISH. 71 

Use the dissecting-pan described under " The Crayfish," 
or put the fish on a large plate. 

1. Notice the shape of the fish as a whole ; hold the fish, 
with the bell j down and the tail toward you, and 
observe that there is an anterior and a posterior 
part, a dorsal and a ventral surface, and that it is 
bilaterally symmetrical. A fish whose body is flat- 
tened from side to side, is said to be " compressed " ; 
the word " flat," when used in describing a fish, 
means flattened from above downward, and is applied 
to such a fish as the flounder. 

Close the mouth of the fish, and measure from the 
foremost point of the head, the tip of the snout, to 
the front edge, the base, of the tail-fin ; this is the 
length of the fish. Measure from the tip of the 
snout to the hinder point of the hard part of the flap 
which covers the side of the head ; this is the length 
of the head. How many times is the length of the 
head contained in the length of the fish? Measure 
from above downward at the deepest part ; this is the 
depth of the fish. How many times is it contained in 
the length ? Compare the width and depth of the fish. 

2. The fins on the back are the dorsal fins ; spread them 
out to their fullest extent, and study them thoroughly: 
their framework consists of fin-rays; some of them 
spinous rays, or spines (unjointed, or inarticu- 
lated), others soft rays (jointed, or articulated) ; 
study carefully one of the soft rays, using a lens: 
count each kind of rays; observe the membrane 
connecting the rays. This membrane is double ; the 
fin is really a fold of the skin, with supporting parts 
within the fold. 



k 



72 PRACTICAL ZOOLOGY. 

Measure along the base of each fin ; this is the 
length of the fin; extend the fin fully, and measure 
the length of its longest ray; this is the height of 
the fin. Compare the length and height of the fin. 
In some fishes the dorsal fin is single ; in others it is 
divided, forming two or more dorsal fins. 

The tail-fin is the caudal fin ; when this fin is sym- 
metrical, or nearly so, the backbone apparently ending 
at the centre of its base, the tail is said to be homo- 
cereal, as in most fishes; if the backbone extends 
into the upper lobe of the fin, making this lobe larger, 
as in the sturgeon, the tail is called heterocercal. 

The fin in front of and below the caudal, is the 
anal (being just back of the external opening of the 
intestine, the anus) ; compare this fin with the dorsal. 

The fins above named, being in the middle line, 
are called median, or vertical fins. 

The remaining fins are called paired fins; the pair 
back of the head are the pectoral fins, and are con- 
sidered as representing the forelimbs of the higher 
animals ; the lower pair (usually farther back) are 
the ventral fins, representing the hind limbs of 
higher animals. Take the ventral fins between the 
thumb and finger to feel their bony support; rest 
the fish on its back, and press the thumb and fore- 
finger of the other hand on the bony structures at 
the bases of the pectoral fins ; move the ventrals 
about to determine, as far as possible 03^ feeling, the 
relations between the bones supporting the two pairs 
of fins. 
3. Open the mouth of the fish by pulling its lower jaw 
down as far as possible ; the bone which forms the 



THE FISH. 73 

border of each side of the upper lip is the pre-max- 
illary; note its extension backward on the middle of 
the snout; observe the fine teeth on it. Observe 
their size, shape, arrangement, and the direction in 
which they point. 

The paddle-like bone back of the pre-maxillary is 
the maxillary. 

The bone on each side of the lower jaw is the 
dentary. Which of these bones bear teeth? Open 
and shut the mouth repeatedly, watching the move- 
ments of these parts, and their relations to each 
other. 

Compare the perch or bass with the sucker in the 
movements of the mouth parts. 

Back of the pre-maxillary, in the front part of the 
roof of the mouth, is a patch of teeth, borne on a 
bone called the vomer ; extending backward from 
the vomer, on each side of the roof of the mouth, are 
rows of teeth on the palatine bones. 

Examine the short tongue; feel its surface with 
the tip of the finger, or scrape it with the head of a 
pin ; examine also the whole of the inside of the 
mouth, to see if there are more teeth than those 
mentioned. Can a fish taste? 

Note the shape and position of the eyes; with the 
handle of the forceps press on the eye at various 
points near its margin, to see its range of motion; 
watch the roof of the mouth while pressing the eye, 
also press outward on that part of the roof of the 
mouth nearest to the eye. Compare the eyes with 
human eyes. Are eyelids present? Observe a thin 
bone imbedded in the skin immediately in front 



74 PRACTICAL ZOOLOGY. 

of the eyes; it is the ante-orbital bone. This and 
several smaller bones just under the eye are known 
as sub-orbital bones. 

5. Examine the nostrils in front of the eyes. How 
many are there ? Probe them with a bristle tipped 
with sealing wax ; do they open into the mouth ? do 
any of them communicate with each other? 

G. The flap at the side of the head is the gill-cover, and 
the opening back of it is the gill-opening. The upper, 
hinder piece of the gill-cover is the opercle; along its 
lower posterior border, and rather closely attached to 
it, is the sub-opercle; in front of the opercle, and 
below and back of the eye, bordering the part known 
as the cheek, is the pre-opercle. If the margin of 
this be toothed, it is said to be serrate ; under the 
pre-opercle, and in front of the lower end of the sub- 
opercle, is the inter-opercle. 

The thin membrane below the gill- cover is the 
branchiostegal membrane; the curved bones sup- 
porting it are the branchiostegal rays; count them. 
The narrow part of the body between the branchio- 
stegal membranes is the isthmus. 

7. Raise the gill-cover and examine the gills: each gill 
has a central bony arch ; on the hind and outer border 
of this arch is a fringe of red gill-filaments; on the 
front and inner border of the arch are the teeth-like 
gill-rakers. Are these alike on all the gills? A red 
streak along the arch, at the base of the filaments, is 
made by the blood-vessels, which bring the blood to, 
and carry it away from, them. 

Thrust a finger into the mouth, and depress the 
tongue. What effect has this on the gills ? what 



THE FISH. 75 

effect on the gill-rakers ? The slits between the gills, 
which allow communication from the mouth to the 
gill-opening, are the gill -clefts. How many gills are 
there ? How many gill-clefts ? After this study of 
the gills in their natural position, remove the fore- 
most gill, severing it at its upper and lower ends, and 
note more fully the parts above named, especially the 
structure and arrangement of the gill-filaments and 
gill-rakers ; tear away some of the filaments, and find 
the groove along the posterior, outer border of the 
bony arch in which run the blood-vessels. Look 
on the inside of the gill-cover for a red spot — the 
false gill. 

8. Observe the arrangement of the scales. Pull out a 
scale and study its shape and markings, the radiat- 
ing and concentric striae. Compare its inner and 
outer surfaces, its anterior and posterior margins ; 
make a drawing of it, naming its parts ; pull out a 
scale from a black spot ; compare that part of its sur- 
face which was exposed with the part overlapped by 
other scales ; scrape the portion that was exposed ; 
thrust one point of the forceps under the hind edge 
of a scale, and watch closely this edge, while slowly 
raising it, to see that a thin skin covers it and passes 
on to the scale behind. This thin outer skin is 
chiefly epidermis. In this epidermis lie the black 
pigment cells which make the dark spots. 

A scale with a smooth hinder border is a cycloid 
scale; if the hinder portion is toothed or spiny, the 
scale is ctenoid. 

9. A raised line along the side is the lateral line. Re- 
move one of the scales on this line, and find what 
makes the line. Is the line continuous? 



76 PRACTICAL ZOOLOGY. 

10. Make a drawing of the fish as seen from one side, 
naming all the parts visible. Describe fully all the 
parts above noted, including the general color and 
markings. 

DISSECTION OF A FISH. 

Hold the fish with its back in the palm of the left hand, 
and the tail towards you ; thrust the point of one blade 
of the scissors obliquely forward through the body-wall, 
just in front of the anus, and cut forward in the middle 
line to the ventral fins. After observing the organs with- 
in, cut upward, i.e., toward the dorsal region of the fish, 
with scissors, from the beginning of the first cut as far as 
possible without cutting anything but the body-wall, being 
especially careful not to cut into the air-bladder which 
occupies the upper part of the body-cavity ; now cut for- 
ward to a point a little above the pectoral fin ; make the 
same cut on the other side; turn forward the flaps thus 
made, noting the silvery membrane, the peritoneum, 
lining these flaps, and study the organs of the body-cavity. 

1. In the front part of the body-cavity is a reddish or 
brownish mass, the liver, lying chiefly on the left side 
of the fish. Raise the hinder edge of the liver, and 
observe how closely it fits the organs next to it. 
Press the liver backward, and observe the hepatic 
veins passing forward from the liver through the 
thin partition in front. 

2. Lay the fish on the right side and turn the liver 
downward, gently tearing away its thread-like attach- 
ments. This uncovers a pinkish sac, the stomach- 
Pass a probe back through the mouth and wide 



THE FISH. 77 

gullet into the stomach, to determine its shape and 
extent. When the stomach ends blindly behind, the 
intestine arising from its front end, the stomach is 
said to be caecal. Compare the stomachs of the 
perch and sucker. Observe a branch of the pneumo- 
gastric nerve distributed over this side of the stomach. 

3. Find a large tube arising from one side of the stomach, 
the intestine. In many fishes there are at or near 
this point several worm-like branches, often matted 
together by fat. Eest the fish on its back, and turn 
the liver to the left, to examine these. Clear away 
this fat, separate these tubes and count them. They 
are pyloric caeca. With scissors make a small hole 
in the end of one caecum; insert the point of a blow- 
pipe and inflate it. 

4. Just beyond the caeca, on the posterior surface of the 
liver, is a thin-walled sac, of a greenish or yellowish 
color, the bile-sac. When empty, it has a worm-like 
appearance. Snip it open with the scissors, or prick 
it with a dissecting needle to see the bile. 

o. Trace the intestine to the anus, observing that it is 
held in place by a thin, transparent membrane, the 
mesentery; observe the blood-vessels in it; tear this 
away in following the intestine; find a small, deep red 
body near the intestine, the spleen. Compare the 
length of the intestine in the perch or bass with that 
of a sucker. The sucker eats vegetable matter, and 
may be called herbivorous ; while the perch and bass 
feed chiefly on other fishes, and are carnivorous. 

6. In the hinder part of the body-cavity are the repro- 
ductive organs; the yellow ovary (varying greatly 
in size, according to the season) in the female, the 



78 PRACTICAL ZOOLOGY. 

two white testes in the male. In some fishes the 
ovary is single, in others it is double. If double, 
the two ovaries unite in one tube, which discharges 
the eggs — the egg-tube, or oviduct. Trace the ovi- 
duct ; has it a separate outlet ? Sometimes the eggs 
in the ovary can be discerned. 

7. Back of the oviduct or hinder part of the testes is a 
small pink sac, the urinary bladder. Look for its 
external opening back of the anus. 

8. In the upper part of the body -cavity is the air- 
bladder. 

Make now a drawing of the organs above noted 
in their natural positions, as seen from below. 

Look closely to see if there is any connection be- 
tween the air-bladder and the stomach; gently scrape 
away the thin outer covering, peritoneum, and note 
its thin wall; examine the whole of this wall to see 
if there are any blood-vessels in it. After thoroughly 
examining, puncture and remove it. 

9. Above the air-bladder, extending along the roof of the 
body-cavity are slender, dark red bodies, the kidneys. 
Look for an enlargement of the kidneys in front of 
the air-bladder ; trace one kidney to its posterior ter- 
mination in the urinary bladder. Cut away all the 
organs thus far studied, except the kidneys. 

10. In front of the liver is a thin partition, the false dia- 
phragm. If this is not already opened, cut carefully 
through it to see the heart ; also cut from the anterior 
end of the first slit in the walls of the abdomen for- 
ward to one side of the ventrals, through the bones 
of the pectoral arch and on through the thick mass 
of muscle, in the middle line, to the isthmus, and pull 



THE FISH. 79 

the walls of this cavity, the pericardial cavity, out 
to the sides. 

The red, angular portion of the heart, which in the 
natural position of the fish lies lowest and hindmost, 
is the ventricle; the darker, more irregular portion 
lying (in the natural position) above the ventricle, is 
the auricle; the larger blood-cavity back of the auri- 
cle, and extending across the body-cavity, above the 
false diaphragm, is the venous sinus; in front of 
the ventricle is the light-colored conical arterial bulb. 
This narrows forward into an artery which gives off 
branches on both sides, one to each gill. Make a 
drawing of the heart and arterial bulb. After passing 
through the gills, the blood-vessels re-unite to form 
the dorsal aorta, w^hich passes backward just under- 
neath the spinal column. From above the gills 
branches also run forward to the head. 
11. Insert the finger into the fish's mouth and depress the 
tongue. Observe the thin membrane which forms 
the floor of the mouth on each side of the tongue ; 
cut through this membrane close to the inner border 
of the lower jaw on each side and across the band of 
muscle which is attached to the point where the two 
halves of the lower jaw unite ; continue the cut back- 
ward on each side between the gill-cover and the 
branchiostegal membrane, and wholly separate them. 
Turn back the whole flap thus loosened, and again 
examine the gills ; note the joints in the gills ; with 
the forceps seize the tongue, raise and lower it, to see 
the action of these joints in the gill-arches. 

Observe, where the gills unite above and below, 
patches of closely set teeth, the superior and inferior 



80 PRACTICAL ZOOLOGY. 

pharyngeal teeth- The bones supporting these 
teeth, above and below, are the pharyngeal bones; 
they represent a fifth gill-arch. Again depress and 
raise the lower ends of the gills, observing how the 
pharyngeal teeth are brought together. What is 
the probable use of these teeth, and what is the work 
done by the teeth previously examined ? 

Again examine the gill-rakers, and observe how 
they are affected by bending and straightening the 
gill-arches. Examine the bone which bears the 
branchiostegal rays, and note with what bones it is 
connected. 

12. Examine the bones in the posterior border of the gill- 
opening; these are together called the pectoral arch. 
The largest of these bones is the clavicle; its upper 
part forms a projection above the base of the pectoral 
fin. Connected with the upper end of the clavicle is 
the supra-clavicle, which, in turn, is connected with 
the skull through the post-temporal. Cut away the 
flaps of the body-wall bearing the fins. 

13. Note also the bones supporting the ventral fins ; these 
are considered as representing the pelvis. In the 
higher fishes the pelvis is fastened to the clavicle ; in 
the lower fishes it is separate from the rest of the 
skeleton and imbedded in the flesh. How is it in 
the specimen you are studying? Carefully remove 
the ventrals, with the bones which support them ; ex- 
amine and describe them, after scraping away all 
muscles and other soft tissues. 

If the dissection of the muscles and the brain are 
not to be made at this time, carefully cut away the 
gills at their upper attachment, and remove them ; 



THE FISH. 81 

wash the fish thoroughly, wipe it dry, and keep it in a 
cool place. 

14. Hold the fish in the left hand, with its back up and 
its head away from you ; insert the point of one blade 
of the scissors at the base of the caudal fin and cut 
the skin forward, passing to the left of the dorsal fin 
and on to the head; remove the skin of this side, 
carefully leaving the white muscles beneath undis- 
turbed ; scrape part of the skin clean on the inside ; 
note the arrangement of the scales as seen on each 
side of the skin ; look also for traces of the lateral line 
on the inside of the skin. Hold the skin up and look 
through it toward the light, alternately stretching and 
shortening it, noting especially the lateral line. Roll 
the skin lengthwise, with the scales outermost, to see 
how the epidermis passes from one scale to another. 

15. Observe the parallel, transverse markings on the mus- 
cles along the body. 

16. Cut and scrape away all the muscle of this side of the 
body down to the bones, and make out the central 
backbone, with its bony projections above and below. 
Bend the dorsal and anal fins from side to side, to 
show the bones which support these fins and the rela- 
tion of these fin-supporters to the projections of the 
backbone. 

17. Break across the backbone under the centre of the 
second dorsal fin, and remove one of the pieces, or 
vertebrae, of the backbone ; clear away all muscle and 
other tissue, and make out the following parts : — 

a. The central body, or centrum, shaped like an 
hour-glass, and hollowed at each end. 



82 PRACTICAL ZOOLOGY. 

b. Two projections extending upward, soon uniting 
to form one spine, the neural spine. 

c. The archway formed above the body of the ver- 
tebra is the neural arch. 

d. A similar arrangement below, forming the haemal 
arch and haemal spine. 

Make a drawing of this vertebra as seen from the 
side ; as seen from the front. 

18. In like manner remove and study a vertebra from a 
point opposite the centre of the first dorsal fin, with 
the ribs attached to it. What are the differences 
between these two vertebrae? 

19. Thoroughly clean the last vertebra, and study care- 
fully its relations to the caudal fin. 

20. Observe the white spinal cord in the canal formed by 
the neural arches above the bodies of the vertebrae. 
This is the nerve-canal, or neural canal; note also 
the blood-vessels in the corresponding blood-canal, or 
haemal canal, below. 

THE BRAIN OF THE FISH. 

Cut off the head ; clear away the muscles at the back 
of the head ; carefully slice off the top of the skull with a 
strong, sharp knife ; with extreme care cut away the roof 
of the brain-cavity ; a mass of loose, gray tissue covers the 
brain, which is of a white or pinkish color ; cautiously 
pick away this loose tissue, using a small syringe to wash 
away the loosened matter. Make out the following parts 
of the brain, beginning at the posterior end : — 

1. The cut-off end of the spinal cord. 

2. The widened part of the spinal cord, where it passes 



THE FISH. 83 

under the hinder part of the brain, is the medulla 
oblongata. 

3. The hinder, undivided part of the brain is the cere- 
bellum. 

4. In front of the cerebellum are the two large, rounded 
optic lobes, forming the widest part of the brain. 

5. In front of the optie lobes are two oval masses which 
meet in the middle line; these are the cerebral hemi- 
spheres, and together they constitute the cerebrum. 

6. Observe the olfactory lobes tapering forward in front 
of the cerebral hemispheres ; from these trace the 
olfactory nerves to the nasal cavities. 

Make a drawing of the brain as seen from above, 
naming all these parts. Cut open one of the optic 
lobes and note that it is hollow ; push the eyes out- 
ward and find a white cord extending inward and 
backward from each. These are the optic nerves, 

THE MUSCLES OF THE EYE. 

1. Cut away the upper part of the eye-sockets and find 
in each a muscle extending outward and backward 
from the anterior part of the socket to the top of the 
eyeball. This is the superior oblique muscle. 

2. Another muscle coming from the posterior part of the 
socket will be seen passing forward to be attached 
under the oblique muscle. This is the superior 
rectus. Make a drawing showing these muscles. 
The other eye-muscles may be more easily examined 
from beneath. 

If the under surface of the skull of the specimen 
previously studied be not injured, it may be used; 
otherwise, cut off the head of another fish, and cut 



84 PRACTICAL ZOOLOGY. 

away completely the lower jaw and the floor of the 
mouth. Move the gill-covers in and out to show 
more clearly the thin plates of cartilage between the 
eyes and the roof of the mouth ; with scissors slit in 
the middle line the tough membrane lining the roof of 
the mouth, and strip it out to the sides. Observe a 
muscle running outward from each side of the base of 
the skull to the corresponding gill-cover. Cut these 
at their inner ends and turn them outward. With 
scissors cut away the cartilages covering the under 
surfaces of the eyes. 

3. Observe a muscle passing outward from the front part 
of the socket to the eyeball, the inferior oblique 
muscle. 

4. The muscle running forward close to the partition 
between the eyes is the internal rectus. 

5. On the under surface of the eye is the inferior rectus. 

6. Attached to the hinder border of the eye is the larger 
external rectus. Note carefully the origin of each 
of these, their place of insertion on the eyeball, and 
their change of shape in their course ; consider the 
effect of each on the eye. 

Observe the thin-walled swellings at the sides of 
the base of the hinder part of the skull; cut into 
these ear-capsules and find in each a membranous 
sac, the vestibule of the ear. In this sac lies the 
" ear-bone" or otolith. Find the white optic nerve 
arising from the inner surface of the eyeball; with 
a sharp knife cautiously cut away the base of the 
skull and trace the optic nerves to the brain ; de- 
monstrate that they cross each other, the optic 
nerve from the right eye entering the left half of 
the brain, and vice versa. 



THE FISH. 85 

Make a drawing showing this view of the brain and 
eyes; open one of the eyes and remove the spherical 
crystalline lens. 

The air-bladder (sometimes called the swim-bladder) is 
believed to be of use to the fish in keeping its place in the 
water. In many fishes the air-bladder is connected with 
the oesophagus by a tube, and in many others there is a 
circulation of blood in part of the wall of the air-bladder. 
The air-bladder really corresponds to the lungs of the 
higher animals. 

Parts of animals having essentially the same structure, 
or corresponding in origin, are said to be homologous. 
Thus the air-bladder of the fish and the lung of the snake 
are homologous. The pectoral fins are homologous with 
the fore limbs of the higher animals, and the hind limbs 
of the higher animals are the homologues of the ventral 
fins of the fish. Parts which are alike in use are said to 
be analogous. Thus the gill of a fish and the lung of a 
man are analogous ; both serve in getting oxygen into the 
blood. 

Analogy is correspondence in use or function. 

Homology is correspondence in structure or origin. 

In some fishes the air-bladder is actually used as a lung. 
These fishes are in consequence called lung-fishes. Some 
of our fishes which breathe by gills have the power of 
living out of water for some time, and are said to crawl 
from one body of water to another when the former 
dries up. 

Fishes are the lowest of the vertebrates; they are also 
the oldest of vertebrates, in the order of their appearance 
on the earth. 



86 PRACTICAL ZOOLOGY. 

The young fishes of all kinds have heterocercal tails, but 
as they grow older, the higher fishes develop homocercal 
tails. The earliest fishes had heterocercal tails, as have 
many of the lower fishes at the present day. 

Again, the early fishes had cartilaginous instead of bony 
skeletons. All young fishes have cartilaginous skeletons, 
but the higher fishes develop bone in place of cartilage as 
they grow older. 

It will be seen then that the stages of development of 
the higher fishes repeat the order of the geologic appear- 
ance of fishes, and review the classification of fishes from 
the lowest to the highest. What do these facts signify? 

Use Jordan's " Manual of the Vertebrates " (latest edi- 
tion), or, better, Jordan and Gilbert's " Synopsis of the 
Fishes of North America," for finding the names of fishes 
as " Gray's Manual " is used for "analyzing" plants. 



THE FROG. 

In the spring frogs gather in ponds and streams to 
breed. Later, they may be found in meadows and fields 
near water. When seeking them in such places walk 
rapidly along so as to frighten and make them jump so 
they can be seen. When studying frogs it is well to get 
a good supply and keep them alive in a box, which should 
be shut securely, leaving a few holes. This box may be 
kept in a cellar or in a watering-trough. Frogs will live 
a long time without feeding. In capturing frogs observe 
how they dive into the mud to escape. 



THE FKOti. 87 



STUDY OF THE LIVE FROG. 

1. Put a live frog into a tub of water and study carefully 
its mode of swimming and floating. 

2. Notice how the frog sits when at rest. 

3. What has the frog in common with other animals that 
jump well ? 

4. Watch closely the frog's breathing, paying especial 
attention to the throat, nostrils, and sides. 

5. Touch the eyeball with a pencil, and note what fol- 
lows. 

6. Note the motions of the eyelids. 

7. What does the frog eat, and how does it take its 
food? 

8. Look for slight pulsations near the end of the back- 
bone on each side, near the anus. These are the 
beatings of the lymph-hearts. 

Make drawings of the live frog in the sitting pos- 
ture. 

EXTERNAL FEATURES OF THE FROG. 

Kill a frog by wrapping it in a towel or piece of cloth of 
any kind, and moistening the latter with chloroform; or 
put a teaspoonful of ether irk a fruit -jar nearly full of 
water, immerse the frog in it, and cap the jar. 

1. Has the frog a neck? Find the division between the 
head and the body by bending the parts and feeling 
for the joint. 

2. Back of and below each eye is an oval area, the mem- 
brane of the ear-drum, or tympanum. 



88 PRACTICAL ZOOLOGY. 

3. The fore limb consists of the arm, forearm, and 
hand. 

4. The hind limb consists of the thigh, leg, and foot. 

5. Count the fingers and toes. 

6. What differences are there between the fore and hind 
limbs ? 

7. Open the mouth, seize the tongue with the forceps 
and draw it forward ; observe that it is attached 
in front, but free behind. How is such a tongue 
used? 

8. Look closely for teeth. Where are they ? 

9. Pass a bristle tipped with sealing-wax into one of the 
nostrils. Where does it enter the mouth ? 

10. Make a small opening in one of the tympanic mem- 
branes, pass a bristle through this opening, and look for 
its appearance in the mouth. The opening through 
which it appears is the Eustachian tube. 

11. The mouth narrows back into the gullet. 

12. In the back part of the floor of the mouth is a small 
slit, the glottis, leading to the lungs. 

13. Compare the colors and markings of the upper and 
lower surfaces of the frog; draw dorsal and ventral 
views of the dead specimen, naming all visible parts. 

INTERNAL STRUCTURE OF THE FROG. 

1. Cut through the skin of the abdominal wall along the 
middle line ; turn the skin back on each side, noting 
how loosely it is attached to the abdominal wall. 
Cautiously avoiding any large blood-vessels, open the 
abdomen lengthwise from the pelvis to the breast- 
bone ; from the hinder end of this slit cut outward on 



THE FROG. 89 

each side and turn back the flaps so as to expose the 
internal organs ; with forceps raise the hinder part of 
the breastbone ; observe the heart lying next it, and a 
thin membrane extending from it to the breastbone ; 
with scissors cut this membrane close to the breast- 
bone ; cut through the breastbone in the middle line, 
and stretch its parts well out to the sides to dis- 
close the heart and surrounding organs. Lay the 
frog on its back; stretch the fore limbs out to their 
fullest extent, and pin them down. 

2. Insert the blowpipe into the mouth and inflate the 
stomach. Study its shape. 

3. Trace the intestine from the stomach to the anus. 

4. An enlargement of the intestine near the anus is the 
cloaca. 

5. The thin membrane which attaches the intestine to 
the back of the abdomen is the mesentery. In a 
freshly killed specimen blood-vessels may be seen in 
the mesentery. Trace these blood-vessels. 

6. The dark liver partly covers the stomach. 

7. Between the lobes of the liver is the greenish bile-sac. 

8. In the mesentery, near the stomach, is the pale pan- 
creas. 

9. Further back in the mesentery is the small red spleen. 

10. If the previous inflation did not reveal the large 
urinary bladder, insert the blowpipe into the anus, 
and inflate the bladder through the cloaca. 

11. In the female, masses of dark, spherical eggs may be 
seen. The eggs are in the ovary, which is very large 
when full of eggs, and much folded and plaited. 

12. The egg-tube, or oviduct, is a long, coiled tube running 
back to open into the cloaca. Cut a small hole in the 



90 PRACTICAL ZOOLOGY. 

oviduct near its anterior end and insert a bristle tipped 
with sealing-wax to discover where the oviduct ter- 
minates anteriorly, and with what it connects at this 
end. 

13. In the male, the yellowish testis corresponds to the 
ovary. 

14. Connected with the ovary or testis are usually found 
slender masses of fat. 

15. The kidneys are two long, deep red bodies alongside 
the backbone, in the hind part of the body near the 
cloaca. 

16. Insert a blowpipe through the mouth into the glottis 
and inflate the lungs; observe their shape, and that 
they are nearly hollow sacs, not spongy all the way 
through as in the lungs of the rabbit or man. When 
a lung has but few cells, only a small quantity of blood 
can come into contact with the air. Such a lung is 
adapted to an animal of low temperature and sluggish 
habits. Tie a thread around each lung while it is 
inflated; cut the lungs out and hang them up to dry 
thus expanded. When thoroughly dried, they may be 
cut open and compared with the lungs of a turtle 
similarly prepared. 

17. The thin sac inclosing the heart is the pericardium. 
Carefully cut it away; time the pulsations as seen in 
a freshly killed specimen. What is the effect of 
applying gentle heat to the heart, as by breathing 
on it? The hinder conical part of the heart is the 
ventricle; farther forward and nearer the back are 
the auricles; running forward from the ventricle is 
the main artery. This divides into two branches, 
each of which has three subdivisions: — 



THE FROG. 91 

a. To the head, the carotid. 

k. To the body generally, the aorta. Trace the two 

aortse, right and left, to their point of union near 

the spleen. 
c. To the lungs and skin, the pulmo-cutaneous. 

Part of the impure blood is sent to the skin, through 
which it gets oxygen. In this way the frog gets 
oxygen when under water for a long time, and during 
the winter, when it hibernates deep down in the mud. 
Remove the heart. Does it beat after removal from 
the body? Note the effect of holding the heart in 
the palm of the hand. Note the effect of pricking it 
with a needle. 

CIRCULATION OF BLOOD IN THE WEB OF A FROG'S FOOT. 

Split a cigar-box cover or shingle in the middle, and cut 
a Y-shaped notch in one end; wrap the frog in a wet 
cloth, with one leg projecting, and tie it thus wrapped to 
the board; tie threads around two of the toes, and stretch 
the web (but not too tightly) over the V-shaped notch ; 
place the board firmly on the stage of the microscope. 
Examine first with a one-inch objective. The large ves- 
sels which grow r smaller by subdivision are the arteries. 
The large vessels which are formed by the union of smaller 
ones are the veins. The finer vessels forming a network 
are the capillaries; the black spots are pigment cells. 
Where these are very abundant, they make dark spots, as 
seen on the frog's back. Take a triangular piece of cover- 
glass a little smaller than the web under examination; 
place a small drop of water on one side of it, and lay the 
glass, with the water downwards, on the web. Put on a 



92 PRACTICAL ZOOLOGY. 

higher power, say a quarter-inch objective, and study the 
little bodies floating in the blood. These are the cor- 
puscles. 

1. The large, faintly colored oval corpuscles; do they 
change their shape when pressed, as in turning a cor- 
ner ? What is the color of these corpuscles ? Mould 
a bit of clay into the shape of one of these bodies. 

2. The smaller, rounded, paler corpuscles, fewer in num- 
ber and moving with a slower and more unsteady 
motion along the sides of the channel ; what must 
be the shape of these ? Place a drop of frog's blood 
on a slide, cover with a cover-slip, and examine with 
a high power. Make careful drawings of the two 
kinds of corpuscles. (Take a small drop of blood for 
this, and after covering it, run a little oil around the 
edge of the cover to prevent drying.) 

THE NERVOUS SYSTEM OF THE FROG. 

The nervous system is better seen in alcoholic speci- 
mens. Slit the skin along the back from the snout to the 
anus ; with a sharp knife cautiously cut away the top of 
the skull, and find : — 

1. Between the eyes, side by side, two elongated white 
bodies, the two halves, or hemispheres, of the cere- 
brum. Observe two small pear-shaped bodies, the 
olfactory lobes, in front of the cerebral hemispheres. 
These taper forward into nerves running to the nasal 
region; these are the nerves of smell, or olfactory 
nerves. 

2. Back of the cerebral hemispheres are the optic lobes, 
forming the widest part of the brain. Prove that a 



THE FROG. 93 

white cord, the optic nerve, connects each of these 
lobes with one of the eyes; does the optic nerve 
extend directly from each eye to the corresponding 
optic lobe ? 

3. Extending backward from the under side of the optic 
lobes is the medulla oblongata. 

4. The medulla oblongata narrows and becomes the 
spinal cord. Trace the spinal cord back into the 
spinal column, cutting away the part of the backbone 
that covers it. 

5. In the middle of the body-cavity find nerves emerging 
from the sides of the spinal column, hence called the 
spinal nerves. Find that several of these, after 
running backward, unite to form one large nerve. 
Trace the nerve down between the muscles of the 
thigh; this is the sciatic nerve. 

KEFLEX ACTION OF THE FROG'S SPINAL CORD. 

Take a live frog, and find, by bending the head, the joint 
between the head and the backbone ; lay the frog on a 
board, and quickly thrust the blade of a knife through 
the body at this joint, and completely sever the spinal 
column and spinal cord. This destroys sensibility, and is 
essentially the same as cutting off the head. After sever- 
ing the cord back of the head, run a wire into the brain- 
cavity and stir it about in order to entirely destroy the 
brain. In a few minutes hang the frog by a hook through 
the jaw. 

1. Pinch the toes; what follows? Repeat the experi- 
ment several times. Pinch the skin near the anus. 

2. Slit the skin along the back side of the thigh ; tear 



94 PRACTICAL ZOOLOGY. 

apart the muscles, and find the sciatic nerve ; with a 
sharp pair of scissors (while watching closely the foot) 
sever this nerve ; what takes place ? 

3. Hang up as before, and pinch the toes of each foot ; 
what difference is now observed? 

4. With the forceps alternately pinch the two ends of 
the severed sciatic nerve ; what takes place as these 
two ends are pinched? 

5. Run a wire down the spinal column, twisting it about 
to destroy the spinal cord ; what occurs while this is 
doing ? 

6. Pinch the toes as before; what results? 

7. Again pinch the end of the sciatic nerve, still con- 
nected with the parts below, being careful to pinch a 
little lower than before. 



THE FROG'S MUSCLES. 

Make a circular cut through the skin at the top of the 
thighs, and pull off the skin of the hind limbs like a pair 
of hose. Notice the pale color of the muscles. The mus- 
cles of the frog's thigh are nearly the same in number and 
arrangement as in man. Notice especially the calf-muscle ; 
the end by which it is attached above, the less movable 
end, is its origin. The muscle tapers into a strong, white 
tendon below. The end of the muscle at its more 
movable end (or its attachment by a tendon at its more 
movable end) is its insertion. 

Observe the thin, transparent membrane covering the 
muscle, the muscle-sheath. Tear the muscle to pieces, 
and note its fibrous structure. Put a bit of the muscle in 
a drop of water on a slide, and cover with a cover-slip ; 



THE FilOG. 95 

examine first with a low, and then with a high power, to 
see the cross-markings of its finest fibres. This kind of 
muscle is called striped or striated. 

THE ACTION OF A FKOG's MUSCLE. 

Entirely remove the skin from one of the frog's hind 
limbs ; sever the limb from the body at the hip-joint ; clear 
away all the muscles of the thigh, carefully preserving the 
sciatic nerve, still connected with the leg below; sever 
the heel-cord below the heel, and separate the calf-muscle 
from the other muscles of the leg, leaving undisturbed its 
attachment above ; just below the knee, cut away the 
shin-bone, with all the muscles of the leg, except the calf- 
muscle ; there should now remain the thigh-bone, with the 
lower part of the sciatic nerve running to the calf-muscle 
suspended below ; tie a string around the thigh-bone, and 
suspend the whole ; hang a slight weight, such as a door- 
key or a pair of scissors, to the tendon at the lower end of 
the muscle ; now pinch the upper end of the sciatic nerve, 
meanwhile closely watching the muscle. 

THE FROG'S SKELETON. 

Clean the skeleton of the frog after dissection. This 
is easier after soaking it in water for a few days. 

1. Note how open and light the skull is, and how easily 
the bones are cut. 

2. Count the parts of the spinal column ; these are the 
vertebrae. The long bone terminating the spinal 
column is the urostyle. 

3. Observe the long bones of the pelvis, parallel with 
the urostyle. What makes the frog hump-backed? 



9b PRACTICAL ZOOLOGY. 

4. The fore limb has, in the upper-arm, the humerus; in 
the forearm the radius (same side as the thumb) and 
the ulna; in the wrist are several small bones, the 
whole collectively called the carpus; in the hand are 
the digits. 

5. The hind limb has, in the thigh, the femur; in the leg, 
a bone which shows, by grooves near its ends, that it 
is formed by the union of two bones corresponding to 
the tibia and fibula of man; the several small bones 
of the ankle are together called the tarsus; the 
bones of the toes are the digits. 

6. Are there any ribs ? 

THE DEVELOPMENT OF THE FROG. 

By wading into a pond where there are frogs, in the 
spring, one can usually see how the eggs are laid. If these 
eggs are watched, they will be seen to produce tadpoles ; 
the tadpoles may be reared ; at first the form is fish-like, 
not only in external form, but in the fact that the tadpole 
has no lungs, but breathes by gills. An opening may be 
seen on one side, through which water reaches the gills. 
Later, the lungs develop, and the gills disappear. How do 
the gills of a tadpole compare with those of a fish ? Is the 
tadpole a fish ? 

Put a small tadpole in a watch-crystal containing water; 
examine the gills under a one-inch objective to see the 
circulation of the blood through them. Has the tadpole 
teeth? Examine its mouth; what does the tadpole eat? 
Open a large tadpole, and observe the long, coiled intestine. 



THE FROG. 97 



THE FROG S RELATIVES. 

Frogs, with toads and salamanders, belong to that class 
of vertebrates called Batrachia. What are the points of 
difference between frogs and toads? " The toad is exceed- 
ingly useful as a destroyer of noxious insects. It is noc- 
turnal in its habits, is harmless, and can be taken up with 
impunity, though it gives out an acrid fluid from its skin, 
which may poison the eyelids." 

How does a tree -toad differ from a common toad? 
Should we say tree-toad, or tree-frog ? Take a tree-toad 
from green leaves, and put it into a white-lined box ; cover 
the box with a pane of glass. Is the tree-toad's color 
affected by this change of surroundings? 

Salamanders are often found in cellars, and under rotten 
logs, and in springs. They are often wrongly called 
lizards. Lizards are scaly, and are true reptiles, and are 
related more nearly to the snakes aud turtles. Salaman- 
ders have smooth bodies ; they are harmless (as also are 
lizards). If you find one, examine it carefully. Salaman- 
ders also develop from a tadpole stage. Some salamanders 
are viviparous. If kept in the dark, they sometimes fail 
to complete their development. The mud-puppy, a large 
salamander found in our rivers, retains its gills through 
life. 

The frogs and toads (tailless Batrachia) rank higher 
than the salamanders (tailed Batrachia), having passed 
through the salamander stage and gone on to a higher, in 
which they have more perfect organs. 

In studying insects, we observed that insects pass through 
a worm-like stage, and that they rank higher than worms. 



98 PRACTICAL ZOOLOGY. 

Geology tells us, from the remains found in the rocks, 
that most of the animals now living are different from 
those of early ages. 

The earlier Batrachians were tailed; they were sala- 
mander-like ; the frogs and toads appeared later. Thus 
the different stages of development of the frog repeat the 
order of appearance of Batrachia in geologic succession, 
and review the classification of Batrachia from the lowest 
to the highest. 



EXTERNAL FEATURES OF THE SNAKE. 

Examine the scales; observe their relation to each other 
and to the skin. A scale having a ridge running length- 
wise in the middle line is carinated; if there be no such 
ridge, the scale is called smooth. How many rows of 
scales are there, not counting the wide plates below? 

These wide plates along the belly, as far back as the 
anus, are the gastrosteges ; count them. The plate 
immediately in front of the anus is the anal plate ; if it is 
of one piece, it is called entire; if of two pieces, it is bifid. 
The plates under the tail are the urosteges; how do they 
differ from the gastrosteges ? count them. Why should 
there be these large plates below instead of the smaller 
scales found on the upper surface? 

Keep a live snake, and watch its breathing movements. 
Does the interval of rest occur after breathing in or after 
breathing out? Touch the eyeball with a stick; can the 
snake wink? Watch the movements of the tongue. 



THE SNAKE. 99 



DISSECTION OF THE SNAKE. 

For dissection get a large specimen ; a live one is better, 
as after severing the spinal cord at the neck (which is 
essentially the same as cutting off the head), the beating 
of the heart may be seen, and the persistent vitality of the 
nerves and muscles serve well to illustrate reflex action of 
the spinal cord. Lay the snake's head on a board, and 
with a knife cut entirely through the spinal column, just 
back of the head; but do not cut off the head. This 
destroys its sensibility. Get a paper of tacks, and a board 
as long as the snake. Lay the snake on its back, with the 
head at one end of the board. Push the point of a tack 
into the mouth at one side, and drive it through the upper 
jaw, leaving the lower jaw free. Repeat with the other 
side. Stretch the snake out straight, and tack through 
the tail, just back of the vent. With the forceps pinch 
up a fold of the skin of the throat, and cut through it 
with the scissors ; continue the cut back along the middle 
line of the belly, being very careful not to cut anything 
within. As the cut proceeds, stretch the skin out at the 
sides, and tack it down every two or three inches. Cut 
away the thin membrane which extends across from the 
ribs on each side, avoiding blood-vessels. 

1. With forceps seize the lower jaw and pull the mouth 
open. Xote how dilatable the mouth is, and how 
loosely the lower jaw is hinged to the upper; note, 
also, that the right and left halves of the jaws do not 
unite in front. Examine closely the teeth, their 
shape and arrangement. 



100 PRACTICAL ZOOLOGY. 

2. Seize the tongue, and draw it forward from its sheath 
in the floor of the mouth. Observe its black, forked 
tip ; tack it down. 

3. Above the tongue find a small opening, the entrance 
to the windpipe. It is called the glottis. 

4. Insert a blowpipe (glass tube) into the throat through 
the mouth; pinch the walls of the gullet closely 
around the blowpipe, and inflate the wide gullet and 
stomach. What does the snake eat, and how does 
he eat? 

5. For inflating the lung, a tube with a small point is 
better ; draw out a small glass tube, and connect with 
a rubber tube ; insert the point in the glottis, and in- 
flate. This locates the pink lung, with its posterior, 
thin walled extension, or air-sac. 

6. Trace, from the glottis to the lung, the ringed wind- 
pipe, or trachea. Only one lung is developed; look 
for the rudiment of the other. 

7. The heart will be noticed on account of its beating; 
the part of it farthest from the head is the ventricle; 
nearer the head find two parts, the right and left 
auricles. These two contract at the same time, just 
before the contraction of the ventricle. The heart is 
in a thin sac, the pericardium ; pinch up a fold of 
this with the forceps, and cut through it, and remove 
that part of it covering the heart, very carefully 
avoiding blood-vessels. 

8. Find a blood-vessel arising from the ventricle just 
between the auricles, and passing forward between 
them, curving around over the gullet to the posterior 
part of the body. This is the main artery, or aorta; 
look for its branches running to the head. 



THE SNAKE. 101 

9. Look also for an artery running to the lung, the 
pulmonary artery. 

10. Find several veins, of a darker color than the arteries, 
leading to the heart. 

11. Alongside the stomach is a dark red body, the liver 5 
a large vein runs along its surface. 

12. Back of the liver is the dark bile-sac, and near this 
the spherical red spleen. 

13. Clear away any masses of fat that may hide organs in 
the posterior part of the body, and again inflate the 
stomach and lung for a more perfect view of these 
organs. 

14. Trace the intestine from the hinder end of the 
stomach to the opening, the anus, at its posterior end. 

15. In the hinder part of the body-cavity may be found 
the reproductive organs, ovaries in the female, testes 
in the male. These both have long tubes, extending 
backward to convey their contents to the posterior, 
dilated portion, the cloaca, of the intestine. 

16. Into the cloaca also open the ducts of the kidneys, 
two reddish, elongated structures. 

17. Count the ribs of one side. 

18. Draw the points of the forceps quickly along the 
muscles over the ribs; note the contraction of the 
muscles that follows ; such contraction of the muscles 
is wholly involuntary (as the brain now has no con- 
nection with the body), and is called reflex action of 
the spinal cord. It is the same kind of action as that 
seen in the case of a chicken with its head cut off. 

Use " Jordan's Manual of the Vertebrates" for finding 
the names of snakes. 



102 PRACTICAL ZOOLOGY. 



THE TURTLE. 

1. The upper part of the shell is the carapace. 

2. The under part is the plastron. 

3. Observe the large sections, or plates, marking the 
shell. How many of these plates are there on the 
carapace ? how many on the plastron ? how are they 
arranged ? 

4. Study the motions of the head, legs, and tail ; observe 
the scales on these parts. 

5. Note the shape of the feet ; for how many purposes 
does the turtle use its feet ? are the feet of all turtles 
alike? Count the claws; compare the front and hind 
feet. 

6. With a strong pair of pinchers seize the head, pull it 
well out, and chop it off; examine the mouth; are 
teeth present ? Is there a tongue ? Look for a third 
eyelid. Compare with the pigeon in this point of 
structure. 

DISSECTION OF THE TURTLE. 

Saw through, or cut with a strong chisel, the bridge 
which connects the carapace and plastron on each side. 
Carefully' raise the plastron, and, keeping the blade of the 
knife or scalpel close to its inner surface, cut away all its 
attachments to the organs within, and remove it entirely. 

1. In front are the bones supporting the fore limbs. 

2. Behind are the bones of the pelvis^ supporting the 
hind limbs. Were these two sets of bones attached to 
the plastron? 



THE TURTLE. 103 

3. A thin membrane covers the internal organs ; through 
it the heart may be seen beating. Cautiously avoid- 
ing blood-vessels, cut away this thin covering, and 
distinguish the following parts of the heart: — 

a. The large, hinder part, the ventricle. 

5. In front, on each side, the two auricles. 

c. Between the auricles are blood-vessels, branching 
toward the head. As in the frog, there are two 
aortse, the right and left, which unite posteriorly. 

4. Make out the following order of the heart's beat: — 

a. The contraction of the blood-vessels leading to the 
auricles. 

b. The contraction of the auricles. 

c. The contraction of the ventricle. 

5. On each side of the heart appears the dark liver,, con- 
sisting of two main lobes, connected by a cross-band. 
Search the liver to find the bile-sac. 

6. Under the left lobe of the liver is the stomach. 

7. From the stomach trace the intestine to the trans- 
verse vent under the tail. 

8. Masses of eggs may be found in the ovary (if a 
female). 

9. Find a large bladder near the pelvis. 

10. Raise the liver to find the lungs; pull forward the 
neck, find the windpipe, and insert a blowpipe. By 
inflating, the lungs may be better seen. When the 
lungs are fully inflated, tie a string tightly around 
the windpipe ; carefully remove the lungs, and hang 
them up to dry. When they are thoroughly dry and 
firm, cut them across, and compare with the lungs of 
the frocr and rabbit. 



104 PKACT1CAL ZOOLOGY. 

11. How does the turtle draw in its head? 

12. How long does the heart beat after the head is 
cut off? 

THE SKELETON OF THE TURTLE. 

1. Clean away the muscles and all soft parts. Boiling 
loosens the outer plates ; these are part of the skin, 
and not of the skeleton proper; they are called the 
epidermal plates. 

2. When these plates are removed from the carapace, 
there appears a series of bones extending outward on 
each side ; these are the ribs, very wide, and united 
by their edges. How many of these flattened ribs 
are there ? 

3. On looking at the inner surface of the carapace, the 
series of vertebrae will be found ; and attached to the 
sides of the bodies of these vertebrae are the heads of 
the ribs. 

4. Along the middle line of the outside of the carapace 
between the ribs of the two sides, is found a series of 
bony plates ; these are the enlarged and flattened pro- 
jections of the vertebrae ; they correspond to the 
spines which make the sharp ridge along the backs of 
most vertebrates. 

5. Compare the bones of the pelvis and of the limbs 
with those of the rabbit. 

For a full account of the anatomy of a turtle, see " How 
to Dissect a Chelonian," by Prof. H. N. Martin and 
Dr. W. A. Moale. 

For finding the names and classification of turtles, use 
Jordan's " Manual of the Vertebrates." 



THE PIGEON. 105 



THE PIGEON. 

If possible, capture the pigeons alive, and kill them in 
the following manner : Open the pigeon's mouth and in- 
sert a pipette containing about a teaspoonful of chloroform 
into the opening of the glottis, at the base of the tongue; 
blow the chloroform into the lungs, being careful that the 
point of the pipette does not slip'out of the glottis. If the 
pigeons are taken alive, it is a good plan to keep them 
fasting for a day, that their crops may become empty. 

Note the shape of the body as a whole, and its adapta- 
tion to rapid passage through the air. 

THE HEAD. 

1. The beak consists of the upper and lower mandibles; 
hold the pigeon's head with one hand, and with the 
other take hold of the tip of the upper mandible and 
prove that it is movable. 

2. Raise the upper eyelid, and look in the front angle of 
the eye for the third eyelid ; seize the edge of this 
with the forceps, and pull it backward over the eye. 
Watch the live bird, to see how it winks. 

3. Brush forward the feathers below and back of the eye 
to find the ear-opening; observe the peculiarities of 
the feathers which cover this opening. 

4. Examine the nostrils; open the mouth and insert the 
head of a pin into the nostril, and probe, to discover 
its place of appearance in the mouth. 



106 PRACTICAL ZOOLOGY. 

5. With the forceps pull forward the tongue for careful 
examination. 

6. Just back of the tongue is the opening, the glottis, of 
the windpipe, or trachea. 

7. The mouth continues backward to become the gullet. 

THE WINGS. 

1. Feel of the wing to make out the division into arm, 
forearm, and hand. 

2. The foremost angle- of the wing is called the bend 
of the wing. To what part of your arm does this 
bend of the wing correspond? Just outside of the 
bend of the wing find the false wing, a cluster of 
short quills, borne on the thumb. 

3. The long quills borne on the hand are the primaries; 
count them. The quills on the forearm are the sec- 
ondaries; count them. When quills are found on 
the arm, they are called tertiaries. 

4. The shorter feathers which overlap these quills above 
and below, are the upper and lower wing-coverts. 

5. Extend the wing; compare its upper and lower sur- 
faces ; observe the shape of the quills, and the way 
they overlap one another ; put all these facts together 
and consider their effect in the down-stroke of the 
wing. What is the result of this arrangement when 
the wing is moved quickly upward ? 

THE LEGS. 

1. Feel of the parts, beginning close to the body, to be 
sure to find the first division of the limb ; this is the 
thigh, or second joint. 



THE PIGEON. 107 

2. Below .this is the leg proper, or drumstick. 

3. The next division is the tarsus; it is a consolidation 
of several bones that were distinct in the young bird ; 
this part of the bird's leg, then, really corresponds 
to the tarsus and metatarsus of the human foot, or 
that part between the ankle and the toes. Where, 
then, is the true heel? 

4. Bend and extend the toes to find how many bones 
there are in each. 

5. The scales on the front of the tarsus are called 
scutella; hence the tarsus of the pigeon is said to 
be scutellate in front; the back of the tarsus of the 
pigeon is reticulated. 

THE TAIL. 

1. Count the quills of the tail; spread the tail to see 
their mode of overlapping; make a diagram to show 
their mode of overlapping as seen from behind ; com- 
pare the middle and outer tail-feathers. 

2. The feathers which lap over the base of the tail are 
the upper and lower tail-coverts. 

3. Raise the upper tail-coverts, to find the conical tip of 
the outlet of the oil-gland ; press the oil-gland to get 
a drop of oil. 

4. In front of the lower tail-coverts is the anus. 

THE FEATHERS. 

1. Pull out one of the large wing-quills and study its 
parts; the central axis is the shaft; the expanded 
part is the vane; the side branches of the shaft are 
the barbs, and the side branches of the barbs are the 



108 PRACTICAL ZOOLOGY. 

barbules. With a lens examine the upper and lower 
surfaces of the vane; then tear one of the barbs loose 
from the barbs in front of and behind it, and study it 
carefully ; again watch closely while tearing two barbs 
apart, to see how the barbules are related to each 
other; now examine the vane of the same quill at the 
very beginning of the vane, near the end that was 
attached to the wing. What is the difference between 
the arrangement of the barbs in these two places? 
Observe the hole in the tip of the shaft; run the 
point of a dissecting-needle along the groove in the 
under surface of the shaft toward the base of the shaft. 
This should lead the point of the needle into another 
opening, communicating with the cavity of the shaft. 
Examine this region with a lens, and determine that 
the two sides of the vane meet at this point. Make 
drawings of a quill, as seen from above and below, 
showing all these points. 

With sharp scissors cut across the middle of the 
quill. Look at the cut end ; observe that the vane is 
attached to the upper edges of the shaft; compare 
the place of attachment of the vane to the shaft, 
with the place of attachment of the wing to the body. 
Cut part of the wider side of the vane, at right angles 
to the barbs; with a lens, or a low power of the 
microscope, examine the edge of this cut. Make 
drawings showing these arrangements of the parts of 
the quill. What are the advantages of such arrange- 
ment? 

2. Take one of the body-feathers, and compare it with 
the quill. In what lies the chief difference ? 

3. Find a feather that is wholly composed of " down," if 



THE PIGEON. 109 

there be such; examine the "down" with a micro- 
scope. 

4. Pick a small part of the breast, and study one of the 
pin-feathers. How does it differ from the feathers 
already examined ? 

5. Feathers correspond to the hairs of mammals; there 
are muscles in the skin of the pigeon, by the action 
of which the feathers may be raised, as when the 
bird is angry, or when taking a dust-bath, just as 
there are muscles in the skin of a dog or cat, or in 
the human scalp, by which the hair is made to stand 
on end. 

6. Study the arrangement of the feathers; do feathers 
grow on all parts of the body ? a fledgling shows this 
point well. Push aside the feathers along the line of 
the ridge of the pigeon's breastbone and examine the 
skin ; do feathers grow here ? Look for other un- 
feathered areas. Note how the feathers overlap. 

7. Pick the feathers from one 3ide of the pigeon, just to 
the middle line ; lay the bird on the feathered side, 
and make a drawing, showing (1) the outline of the 
feathers ; and (2) the outline of the body within. 



DISSECTION OF THE PIGEON. 

Pluck the pigeon before dissecting it ; dipping the bird 
in hot water makes this easier. 

1. Insert a tube into the mouth and inflate the crop, 
compressing the neck to prevent the escape of the air. 
Note the shape of the crop. 

2. Beginning at the posterior end of the breastbone, cut 



110 PRACTICAL ZOOLOGY. 

through the skin along the line of the ridge, or keel, 
of this bone, and loosen the skin on each side, con- 
tinuing forward over the crop, being careful not to 
tear the crop ; again inflate the crop, and examine it- 
more fully. Observe the fine lines running crosswise 
and lengthwise in the walls of the crop ; these are the 
muscle-fibers, transverse and longitudinal. Glands in 
the lining of the crop secrete a milky liquid, in the 
breeding season, to act on the food and soften it ; this 
softened food is brought up from the crop and put 
into the mouths of the young pigeons. 

3. Loosen the crop from the front of the breast and from 
the neck. 

4. Find the windpipe, or trachea, with its white rings of 
cartilage. 

5. On each side of the neck is a vein and a white cord, 
the pneumogastric nerve; the vein is the jugular 
vein. If it does not show distinctly, let the bird's 
head and neck hang over the edge of the table, and 
the vein will soon fill with blood. 

6. Insert the tube into the glottis, and inflate ; observe 
the swelling of the whole body, and the inflation of 
the thin-walled air-sacs in the hollow in front of the 
breastbone. 

7. Slit the skin back over the abdomen to the anus, 
loosen it well back on each side, and cut through the 
abdominal wall just behind the breastbone; inflate 
once more, and observe the abdominal air-sacs. 

8. Break the bone of the upper-arm, the humerus, cut 
through the skin and muscles, and push out through 
this opening the end of the bone next to the body ; 
note that it is hollow ; slip one end of a rubber tube 



THE PIGEON. Ill 

over the end of the bone, and inflate; what is the 
result of this experiment? Keeping another tube 
connected with the windpipe, determine whether air 
can be sent in through the windpipe and out of the 
humerus, and vice versa. 
9. Cut through the body-wall, just behind the margin of 
the breastbone forward as far as the ribs; raise the 
breastbone and find the reddish brown liver. 

10. Lift the liver and disclose, at the left of the body- 
cavity, a hard mass, the gizzard- Slit the abdominal 
wall in the middle line back to the anus, push aside 
any fat that may cover the internal organs, and turn 
the gizzard to the left of the bird to find where the 
intestine arises from it ; trace the intestine from the 
gizzard backward. 

11. The part of the intestine nearest to the gizzard is 
the duodenum. 

12. In a long loop formed by the duodenum is a pinkish 
organ, the pancreas. 

13. Trace the intestine, tearing away the fat and the thin 
walls of the abdominal air-sacs, observing that it is 
held in place by a thin, transparent membrane, the 
mesentery. 

14. Near its end the intestine lias two short side branches, 
the caeca. 

15. Just before the intestine ends, it widens, forming the 
cloaca. 

16. Turn the gizzard to the right of the bird ; entering 
it from the front, find a mottled, bulging tube, the 
glandular stomach; pull the crop forward, to show 
the connection between it and the glandular stomach. 
To the right of the glandular stomach is the small, red 



112 PRACTICAL ZOOLOGY. 

spleen; seize the gizzard, pull it backward, and cut 
off the glandular stomach as far forward as possi- 
ble ; remove the gizzard and intestines. Note the 
relations of the tubes which enter and leave the sriz- 
zard; open the gizzard, observing the thick outer 
muscular coat, from which the gizzard is sometimes 
called the muscular stomach. Note also its tough 
lining; examine the contents of the gizzard; why 
does the gizzard have such a thick coat of muscle? 
do all birds have this kind of gizzard ? 

17. In front of the liver is the heart, in a thin sac, the 
pericardium. Cut through its posterior wall, and 
turn the heart forward, to see the dark vein, the 
inferior vena cava, running to it from the liver; pull 
the heart backward, to see the whitish arteries run- 
ning forward from it. The main artery runs forward, 
and turns to the right before going backward, while in 
man the corresponding artery turns to the left. Prick 
a hole in one of the large veins near the heart ; insert 
the point of a blowpipe, and inflate the heart ; its red, 
conical part is composed of the ventricles; the dark 
base is made up of the two auricles. Tie a thread 
around the veins at the anterior and posterior borders 
of the liver, and cut this organ away. 

18. On each side are the pink lungs. Pick away the thin 
membranes bordering the outer hinder borders of the 
lungs ; look for holes through which the lungs com- 
municate with the abdominal air-sacs; look for the 
trachea. Remove the lungs, not failing to see how 
closely they are attached to the back, being indented 
by the ribs. 

19. In the hinder part of the body-cavity are the dark- 



THE PIGEON. 113 

colored, irregular kidneys. Tear them away, observ- 
ing how they are composed of several lobes, which fit 
into the hollows of the pelvis. After removing the 
kidneys, observe the white nerves extending outward 
from* the sides of the spinal column to pass to the 
thighs. 

20. In front of the kidneys are the reproductive organs; 
the two white oval testes, in the male ; in the female, 
the ovary, often showing many eggs in different 
stages of development. The kidneys and reproduc- 
tive organs send tubes to the cloaca ; the tube which 
conveys the eggs from the ovary to the cloaca is the 
oviduct. 

21. Remove the heart, cut off the auricles, and look down 
into the ventricles ; cut across the middle of the ven- 
tricles, and make a drawing of this cross-section. 

22. Cut down into the muscle of the breast, close along- 
side the ridge (keel) of the breastbone, and around 
the outer border of the breastbone ; thus loosen and 
raise a great flap of muscle, the pectoralis major. 
Note the nerve and blood-vessels entering its inner 
surface ; separate it from a smaller muscle lying under 
it, which will be known by the glistening appearance 
of the muscle-sheath; sever the attachment of the 
pectoralis major to the breastbone, and all other 
organs except at the extreme front end ; here the 
muscle narrows into a tough, white cord, or tendon ; 
trace this tendon to its attachment to the bone of the 
arm ; now lay the pigeon on its back in one hand, and 
pull this muscle backward, noting the effect on the 
wing. In like manner loosen all the posterior attach- 
ments of the muscle which was covered by the pec- 



114 PRACTICAL ZOOLOGY. 

toralis major, lying in the angle between the keel of 
the breastbone and the body of the breastbone ; prove 
its action, this time holding the pigeon right side 
up. Compare these two muscles in size, and in the 
amount of work they have to do. The smaller muscle 
is the pectoralis minor. The hinder attachment of 
each of these muscles is called its origin ; and the 
place of attachment of the tendon to the wing-bone is 
the insertion. 

23. Observe the fold of skin extending across the angle 
between the arm and forearm ; dissect away the skin, 
and find a membrane within the skin-fold. 

24. Observe the muscles connecting the hinder edge of 
the breastbone and the pelvis (which were cut through 
in opening the abdomen) ; these are the abdominal 
muscles. How does the bird perform the act of 
breathing ? Compare the bird, snake, frog, and man 
in their modes of breathing. 

25. Bend the leg up close to the body, to the position of 
perching ; what effect does this bending of the leg 
have on the toes ? How does the bird stay securely 
on the perch when asleep? Dissect the leg to find 
the mechanism by which the toes are clenched as the 
leg is bent. 

26. Clean away as much as possible of the soft tissues, and 
keep the skeleton for later study. 

27. Dissect out the tongue, and compare it with the tongue 
of the snake. The voice is produced in the lower 
part of the windpipe, instead of in the upper part, as 
in man. 



THE PIGEON. 115 



THE BRAIN OF THE PIGEON. 

Cut away the top of the skull with a sharp knife, using 
great care not to injure the soft brain, and make out the 
following parts : — 

1. In front, the large cerebrum, consisting of two hemi- 
spheres, which are separated by a deep groove. 

2. Behind the cerebrum is the undivided cerebellum. 

3. Running backward from the under side of the cere- 
bellum is the spinal cord; trace it back into the 
backbone. Make drawings of the brain, as seen from 
above and as seen from the side. 



THE SKELETON OF THE PIGEON. 

Notice the lightness of the whole skeleton. What part 
of the pigeon's weight is bone? Compare the eye-cavity 
with that of man. The lower jaw does not join the skull 
directly, as in man, but is joined to an irregular bone, 
which, in turn, joins the skull. This is the quadrate bone= 
The hole by which the spinal cord leaves the brain-cavity 
is the occipital foramen; in front of this foramen is a 
little rounded projection, the occipital condyle. Observe 
how this condyle fits into a cavity in the first vertebra of 
the neck. Count the vertebrae of the neck, or cervical 
vertebrae. Observe the consolidation of the vertebrae in 
the back; note the joint in each rib, and the arrangement 
for bracing the ribs together. Press the breastbone alter- 
nately toward the back and away from it, meanwhile 
watching the joints in the ribs. 



116 PRACTICAL ZOOLOGY. 

The "wishbone" corresponds to the two " collar-bones " 
of man. Alongside the two branches of the wishbone is a 
pair of strong bones ; what especial need of such bones 
in this place ? In the wing find, in the arm, the humerus ; 
in the forearm, the ulna and radius- The hand has only 
part of the fingers developed; a little bone, representing 
the thumb, is present (which bore the feathers of the 
" false wing"). In the thigh is the femur; in the leg is 
the tibia; and alongside it, the small fibula. The bone 
above the foot represents the consolidated bones of the 
human ankle and foot as far as the toes. What evidence 
is there of such consolidation ? 

Read " The Anatomy of the Pigeon," in Packard's 
" Zoology" and in Parker's " Zootomy"; also "Handbook 
of Vertebrate Dissection. Part II. How to Dissect a 
Bird," by Martin and Moale. 

Trace the pigeon to its family by the aid of Jordan's 
u Manual of the Vertebrates." Use the same book, or 
Coues' " Key," for finding the name of any of our wild 
birds. 



THE HEN'S EGG. 

So place a hen's egg in a basin of water that it cannot 
roll, mark the upper side plainly, and boil it hard; keep 
track of the side that was uppermost. 

1. Crack the shell, and pick it away ; put a piece of it in 
strong vinegar, or other acid. Of what is the shell 
made ? 



THE HEN'S EGG. 117 

2. Note the thin membrane lining the shell. 

3. Does the egg completely fill the shell ? Where is the 
air-space ? Does the lining membrane, in this region, 
adhere to the shell or to the " white " ? How can a 
fresh egg be distinguished, without breaking ? Does 
a fresh egg^ in water, lie in the same position as when 
on a table ? What is the use of this air-space ? 

4. How is the yolk situated in the white ? how in refer- 
ence to the position during boiling? Compare a num- 
ber of eggs, to see if there is any regularity about this. 

5. Note the round spot on the yolk, where it comes near- 
est to ^ the surface. This is the germ-spot, in which 
the chick begins to form. 

6. With a sharp knife, split the egg lengthwise. Is the 
white alike throughout ? is the yolk alike throughout ? 
has the yolk a coat? Cut and tear these parts to make 
out their structure, if they have any definite structure. 

7. Boil an egg hard, as before ; mark a line lengthwise 
around the egg, passing through the point that was 
uppermost while boiling; carefully break away the 
shell on one side, and with a clean cut remoye this 
half of the white and yolk ; place the other half in 
the position it had while cooking ; make a drawing of 
this section, using different colors to show the shell, 
shell-membrane, air-space, white, yolk, germ-spot, etc. 

8. Prop an egg on end, and boil in this position; is the 
yolk in a different position in consequence? The 
white of the egg lias interlacing fibres and partitions 
which keep the mass together; the white cannot be 
mixed with water till these membranes are cut or 
broken; hence an egg, to be eaten raw, should be 
whipped to break these membranes. The white is not 



118 PRACTICAL ZOOLOGY. 

a part of the true egg. In dissecting a bird, the eggs, 
of various sizes, according to their stages of develop- 
ment, may be found in the ovary. At this time the 
egg consists of the yolk, with a thin coat; the white 
is deposited around this later during its descent 
through the oviduct; the shell is last formed, and is 
absent in the case of most animals. 

In the development of birds all their nourishment, 
before hatching, must be stored in the egg ; hence its 
large size. In the higher animals the egg is retained 
in the body of the mother, and gets its nourishment 
from her blood, which circulates through the embryo, 
9. Set a hen on a dozen eggs; mark the date; open and 
examine an egg each day ; if the egg was fertilized, 
the cells of the germ-spot multiply by division, and 
soon take definite arrangement; at the end of twenty- 
four hours the backbone is outlined; during the 
second day the brain begins to develop, and the heart 
appears , on the fourth day the legs and wings make 
their appearance as flattened buds ; until the sixth day 
it would be impossible to say whether the embryo was 
that of a bird, a reptile, or a mammal ; after this, the 
characters peculiar to birds become evident, the feath- 
ers begin to develop, and, later, the particular kind of 
bird may be recognized. 
The development of the rabbit, guinea-pig, or any mam- 
mal, including even man, follows nearly the same order as 
in the chick, the chief differences arising from the fact that 
the embryo mammal develops in a special portion of the 
oviduct, the uterus, or womb, and that the growing germ 
is supplied with maternal blood. 

The eggs of mammals are very minute. These eggs (if 



THE RABBIT. 119 

fertilized) go through the process of division, or segment- 
ation, as described for the sea-urchin. 

In the embryo of the dog it is twenty-five days before it 
can be told whether it is to be a mammal or not, and it 
requires a much longer time to show the distinction be- 
tween the human embryo and that of the dog. The human 
embryo and the embryo of one of the higher apes are so 
closely alike that they are indistinguishable for a still 
longer time than is necessary to distinguish between the 
embryos of dog and man. 

The study of development is called embryology. 

Egg-laying animals are called oviparous. If the young 
develop within the body of the parent, receiving nourish- 
ment from the blood of the parent, the animal is said to be 
viviparous; "or, the young may complete its develop- 
ment while the egg remains in the interior of the body of 
the parent, but quite free and unconnected with it, as in 
those vertebrates which are termed ovo-viviparous." 



THE RABBIT. 



EXTERNAL FEATURES. 



Note the shape of the body ; the relative size of the 
fore and hind limbs ; the length of the ears. Compare 
the soles of the feet witli those of the cat. How 
many toes has each foot, and how do the claws differ 
from cat's claws? 

Make a seiies of dots showing the tracks made by a 
running rabbit, indicating by which foot each track is 



120 PRACTICAL ZOOLOGY. 

made, and showing by an arrow the direction in 
which the rabbit was going. 

3. Observe the "whiskers" on the upper lip. Examine 
the nostrils and the cleft in the upper lip. 

4. Note the chisel-shaped front teeth, the incisors; ob- 
serve the space between the incisors and the grinding 
teeth, or molars. 

5. Observe the hairiness of the inside of the cheek. 

6. Find the third eyelid. How does it compare with 
that of the pigeon ? 

7. Save a few of the hairs, and later examine them under 
the microscope. 

INJECTION OF THE RABBIT. 

Before beginning dissection it is well to have at least 
one specimen injected for the sake of comparison. The 
method of injecting recommended by Parker ("Zootomy") 
has given good results. Kill a rabbit with chloroform ; 
as soon as it is dead, open the thorax by cutting through 
the sternal ribs of both sides, sufficiently far from the 
middle line not to injure the mammary arteries; cut 
across the posterior end of the sternum, and turn it for- 
ward ; slit open the pericardium, and make a large incision, 
by a single cut with the scissors, in each ventricle ; all this 
should be done very rapidly, if possible before the heart 
has ceased to beat, as it is desirable to get rid of as much 
blood as possible; pass a ligature round the aorta close to 
its exit from the heart, and give it a single loose tie ; when 
the bleeding has ceased, sponge the blood from the heart, 
and pick away any clots that may have formed in the left 
ventricle ; pass a cannula through the incision in the left 



THE RABBIT. 121 

ventricle into the aorta, tighten the ligature, and knot it 
firmly. 

If an injecting-syringe be not at hand, use as a cannula 
a glass tube so drawn out as to have a notch in it that it 
may be firmly tied; slip on the outer end of this a short 
piece of rubber tubing, and insert into this the nozzle of 
an ordinary syringe. 

For the injection mass, fill an ordinary tumbler half full 
of fine plaster of Paris, colored with a little carmine or 
yellow ochre ; fill the tumbler with water, stir well, and 
immediately strain the liquid through coarse muslin into a 
second tumbler. Fill the syringe and inject immediately, 
as the plaster soon sets. Give a steady, even pressure. 
On removing the svrin£e. the rubber tube should be 
plugged to prevent escape of the liquid. 

If the specimen be not injected, the veins can usually be 
distinguished from the arteries by their greater diameter, 
thinner walls, and by being of a darker color, retaining 
the blood, while the arteries are usually empty or nearly 
so. 

ORGANS OF THE ABDOMIXAL CAVITY. 

1. Slit the skin in the middle line from the breastbone 
to the pelvis, and strip it well back to the sides. 
Observe the thin abdominal muscles, which form 
the ventral wall of the abdomen. Carefully slit the 
abdominal wall in the middle line from the pelvis to 
the breastbone; from the middle of this slit cut out- 
ward on each side and turn back the flaps. 

2. The lining of the abdomen is the peritoneum; what 
does it tell the sense of touch? 

3. Observe the coiled intestine, noting any variations in 



122 PRACTICAL ZOOLOGY. 

size, shape, or markings, but do not now move any 
part from its natural position. 

4. In the front part of the abdomen the dark-colored 
liver may be seen, overlapping the stomach, and in 
the hinder part of the abdomen there may be seen the 
bladder, varying greatly in size and appearance ac- 
cording to its state of distension. 

5. Pull the intestine backward, and make out the shape, 
size, position, and color of the stomach. Observe how 
the liver and stomach fit together ; push the liver 
forward, and turn the stomach back to find a white 
tube entering its anterior surface ; this is the gullet, or 
esophagus. Just back of the stomach is a small red 
body, the spleen. 

6. Find now the connection between the stomach and 
intestine. Make a drawing of the stomach showing its 
shape and the connections with the gullet and intestine. 

7. Trace the intestine ; that part which forms a long 
loop near the stomach is the duodenum. Within 
this loop is an irregular, fatty-looking mass, the 
pancreas. Find the pancreatic duct entering the 
intestine. This is more easily found in the dog. 

8. Observe that the intestine is held by a thin membrane 
in which are branching blood-vessels ; this is the 
mesentery ; find its supporting attachment. In trac- 
ing its course drag the intestine out of the abdominal 
cavity, but do not tear the mesentery. 

9. The large greenish side-branch of the intestine is the 
caecum. All the intestine from the stomach to the 
entrance of the caecum is the small intestine; that 
part of the intestine posterior to the entrance of the 
caecum is the large intestine. 



THE RABBIT. 123 

10. Turn the stomach and intestines over to the right (of 
the animal), and observe a pink tube, the main artery, 
or aorta, running along the middle of the dorsal wall 
of the abdomen. Following this backward, find a 
branch which subdivides and sends branches to the 
stomach, liver, and spleen. Farther back a branch is 
given off to the intestine ; follow it as it branches 
through the mesentery ; this is the anterior mesen- 
teric artery. Find a branch, the renal artery, of the 
aorta running to the dark-colored, bean-shaped, left 
kidney; finally, the dorsal aorta divides into the two 
common iliacs, extending toward the hind limbs. 

11. Turn the stomach and intestines to the left, and 
observe the two veins running forward from the hind 
limbs; these are the external iliac veins, and by 
their union they form the vena cava inferior. 

12. Observe the branches derived from the right and 
left kidneys, .the renal veins. Compare the positions 
of the right and left kidneys. 

13. Trace the vena cava inferior to the liver. Observe 
the vein which gathers the blood from the intestines, 
the mesenteric vein; the mesenteric vein is joined 
by a vein coming from the spleen, the splenic vein, 
and by the gastric vein, from the stomach; these 
form the portal vein, running to the liver; this vein 
distributes the blood through the liver ; the blood is 
re-collected and empties into the vena cava inferior 
through the hepatic veins, which are almost wholly 
concealed by the liver. 

14. Turn the liver forward, and find on its posterior 
surface the dark bile-sac. The bile-duct, by which 
the bile is conveyed into the intestine, as also the 



124 PRACTICAL ZOOLOGY. 

pancreatic duct, is more easily traced in the dog. 
By probing with a bristle tipped with sealing-wax 
these ducts may be traced. 

15. Pull back the liver, and examine the thin muscular 
partition, the diaphragm, which extends across the 
body, separating the chest cavity, or thoracic cavity, 
from the abdominal cavity. The thin, transparent 
central part of the diaphragm is its tendon ; through 
this the pink lung, still distended, may be seen. 
Keeping the eyes fixed on the lung, prick a hole 
through one side of the diaphragm, and note the 
collapse of the lung. Is the lung on the other side 
affected by this operation ? 

16. Note the passage of the gullet, aorta, and vena cava 
inferior through the diaphragm. 

17. Tie the gullet in two places half an inch apart, and 
cut through between them. Also double-ligature the 
hinder part of the large intestine, the rectum, and 
sever it. Remove the stomach and intestines, care- 
fully cutting the mesentery along its whole attachment 
to the intestine, and uncoil the latter. How many 
times is the length of the body, including the head, 
contained in the length of the intestine? Compare 
the lengths of the small intestine, ccecum, and large 
intestine. Cut out about an inch of the small intes- 
tine in the middle of its course, slit it open length- 
wise, wash it thoroughly, and examine, under water, 
its inner surface with a lens, to see the thread-like 
projections, or villi. In the same way examine a 
piece of the large intestine. These points may be 
made out in the intestine of a dog, or from specimens 
of the calf's intestine obtained from the butcher. 



THE RABBIT. 125 

Preserve both specimens in alcohol. Ligature the 
vena cava inferior just back of the diaphragm and 
just back of the liver, and cut away all of the liver 
but that part immediately surrounding the vena cava 
inferior. To trace the lacteals and the thoracic duct, 
feed a kitten or puppy on rich milk, and three hours 
after place it in a box or under a bell-jar with a 
sponge soaked with ether or chloroform. When it is 
completely dead, cut off its head, open the abdomen, 
spread out the mesentery, and observe in it the white 
lymphatic vessels, known as lacteals, alongside the 
veins, converging to form the thoracic duct. Trace 
this along the aorta. Compare with a kitten that has 
been fasting eight or ten hours. 

THE KIDNEY. 

The structure of the rabbit's kidney may be made out 
by the following directions, but the sheep's kidney, being 
larger and essentially similar, may be conveniently used. 
If the sheep kidney be used, its dissection may be made 
later. 

1. Observe the depression in the inner border of the 
kidney, the sinus. 

2. From the sinus trace a slender white tube, the ureter, 
back to the bladder. Find also the renal artery and 
vein branching as they enter the kidney through the 
sinus. 

3. With a sharp knife split the kidney like a bean, 
beginning at the outer border, stopping the cut when 
a white membrane is reached near the sinus. With 
forceps pry about to explore the cavity between this 



126 PRACTICAL ZOOLOGY. 

white membrane and the body of the kidney. Note 
the branches of this cavity into the kidney. Note 
also the extension of the white membrane into these 
cavities. Make out that the blood-vessels extend 
through these white branches to the outer parts of 
the kidney. Count these branches. 

4. In the center of the white membrane find the opening 
of the ureter, through which the urine is conveyed to 
the bladder. Pass a probe through this opening into 
the ureter. 

5. Note the difference in color of the outer and inner 
parts of the kidney. At the line of change of color 
find where the blood-vessels first branch into the real 
kidney substance. Examine carefully the cut surface 
of the kidney to see its markings. 

6. Make a drawing of one-half of the kidney as seen 
from the inside, showing all the above-named points. 

7. Cut across the middle of the kidney at right angles to 
its length, and make a drawing of this cross-section. 
The projection of the kidney substance into the cavity 
opposite the ureter is the urinary pyramid, and from 
its apex, through many fine holes, issues the urine 
which the kidney has secreted from the blood. 

THE BRAIN AND SPINAL CORD. 

1. Slit the skin along the middle of the back from the 
nose to the tail, and strip it back well to the sides. 
Dissect away the muscles from the back of the head 
and the fore part of the neck ; between the skull and 
the first vertebra, or atlas, is a space covered by a 
thin membrane, through which the white spinal cord 



THE RABBIT. 127 

may be seen. Insert the point of one blade of a pair 
of strong scissors, or bone-forceps, at one side of the 
spinal cord, and cut this side of the arch of the atlas ; 
repeat with the other side, and continue thus through 
several vertebrae, raising and turning them back. 
Observe the coat which covers the spinal cord and 
lines this canal in the backbone, the neural canal. 
Note the groove along the center of the cord. 

2. Turn now to the head and insert one blade of the 
bone-forceps at one side of the entrance of the spinal 
cord into the skull. Cautiously cut and break away 
the whole roof of the skull. This work may be done 
with a strong knife, but the bone-forceps are best. 
The tough membrane covering the brain and adher- 
ing to the skull is the dura mater. 

3. The fore part of the brain is the cerebrum; observe 
the groove separating it into the right and left hemi- 
spheres. Observe the shape of the cerebrum, and the 
general character of its surface. 

4. The prolongations of the cerebral hemispheres be- 
tween the eyes are the olfactory lobes. 

5. Back of the cerebrum is the cerebellum. The partial 
bony partition between them was probably noticed in 
removing the roof of the skull. 

6. The part of the spinal cord within the skull is called 
the medulla oblongata. Make a drawing of the 
brain. If there be enough time, postpone 7 and 8 till 
the completion of 9-17. Carefully cut away the 
dura mater over the brain. 

7. Cut through the olfactory lobes at the front of the 
cerebral hemispheres, and carefully pry up the front 
end of the cerebrum. Running forward and outward 



128 PRACTICAL ZOOLOGY. 

from the base of the brain will be seen the optic 
nerves. Cut these close to the bone beneath. 

8. Back of the optic nerves are the small third and 
fourth pairs of nerves, then the larger fifth, the small 
sixth, and close together the seventh, the facial, and 
eighth, the auditory, and farther back four more 
pairs. Cut these all where they leave the brain-cav- 
ity. 

If 9-17 are not to be done the same day, the spinal 
cord may now be cut an inch back of the brain, and 
the brain be put into alcohol for later study. 

9. Lay the rabbit on a narrow box, and let the head 
hang over one end. Cut away as much as possible 
of the muscle along the backbone. With the bone- 
forceps unroof the whole length of the spinal cord in 
the manner before described. 

10. Note carefully the variations in the diameter of the 
spinal cord in its course. 

11. Observe the spinal nerves, passing off in pairs 
through the spaces between the arches of the verte- 
brae. Count the pairs of nerves, and compare them 
in size in the different regions of the backbone. 

12. Carefully cut away the bone and other tissue around 
some of the nerves in the region of the shoulder, and 
make out that each spinal nerve has two roots, an 
upper, in the natural position of the animal, and a 
lower. These get their names from human anatomy, 
the former being the posterior root, and the latter 
the anterior root. Trace them to their union in the 
one spinal nerve. 

13. On the posterior root, just before it joins the anterior, 
find a swelling, the ganglion of the posterior root. 



THE RABBIT. 129 

14. In the region of the shoulder carefully trace several 
nerves on each side as they unite to form the brachial 
plexus, branches from which supply the fore limb. 

15. In the region of the hips, in like manner trace sev- 
eral large nerves to their union in the lumbo-sacra! 
plexus, the main nerve from which may be followed 
down the back of the thigh, the sciatic nerve. 

16. Compare the color of the brain with that of the spinal 
cord. 

17. Make a drawing of the brain and spinal cord. Re- 
move the brain and cord with the plexuses, and put 
the whole into alcohol. 

THE BRAIN OF THE KABBIT. 

(Alcoholic Specimen^) 

The brain of a cat or dog is better, being larger. Take 
a brain well hardened in alcohol, or a strong solution of bi- 
chromate of potash, and review the parts as named above. 

1. Press down the cerebellum to see the deep groove 
between it and the cerebrum. The thin membrane 
covering the brain and dipping into the grooves is 
the pia mater. 

2. Press down the medulla oblongata, and tear away the 
pia mater where it passes from the cerebellum to the 
medulla oblongata. Xote, between the medulla and 
the cerebellum, a space covered by a thin membrane. 
Cut through this membrane; the cavity is the fourth 
ventricle of the brain. Observe the two ridges 
bounding the sides of the fourth ventricle. At their 
point of divergence, observe the opening of the central 
canal of the spinal cord. 



130 PRACTICAL ZOOLOGY. 

3. Gently separate the cerebral hemispheres, and note 
the transverse band of white fibres connecting them. 

4. Examine the under surface of the brain and find the 
roots of the cranial nerves. 

The olfactory lobes (probably cut or broken off) 
extend forward from the fore part of the cerebral 
hemispheres. 

Note that the optic nerves join each other before 
reaching the brain. Only the first and second pairs 
of cranial nerves directly enter the cerebrum. 

Further back is the third pair of nerves. 

The fourth pair extend up on each side into the 
groove between the cerebrum and cerebellum. 

Back of these is the larger fifth pair. This pair 
supplies part of the face and sends branches to the 
teeth. It is the nerve affected in neuralgia of the 
face. 

Back of, and inside of, the fifth pair is the smaller 
sixth pair. The third, fourth, and sixth pairs control 
the movements of the eyeballs. 

The seventh pair are larger and are farther back 
and outward. These are facial nerves, and control 
the muscles of the face and the facial expression. 

Close to the seventh is the eighth or auditory 
nerve. 

The ninth, tenth, and eleventh arise close together 
further back, and well up on the side of the medulla 
oblongata. 

The ninth supplies the back of tongue and the 
pharynx, and is called the glosso-pharyngeal nerve. 

The tenth pair pass down out of the brain-cavity, 
give off branches to the pharynx and larynx, and are 



THE RABBIT. 131 

distributed to the heart, lungs, and stomach ; hence 
the name pneumogastric nerves. 

The last pair of cranial nerves, the twelfth, arise 
nearer the middle line of the medulla oblongata. 
This pair supplies the muscles of the tongue and are 
called the hypoglossal nerves. 

Draw the brain as seen from below, showing all 
these nerves. 

5. Separate the cerebral hemispheres, and with a sharp 
knife split the brain lengthwise in the middle line. 
Make a drawing of the inner face of one-half. Note 
the branching arbor vitae, of the cerebellum. Trace 
the cavities of the brain. 

6. Trace the blood-vessels of the brain. For this the 
brain of an injected rabbit or dog should be used. 

7. Cut and examine cross-sections of the spinal cord 
after it has been hardened in alcohol. Compare the 
colors of the inside of the brain and spinal cord. 

ORGANS OF THE THORACIC CAVITY. 

1. Remove the skin from the throat and chest. With 
scissors cut through the rib-cartilages along one side 
of the breastbone, slightly separate the edges of the 
cut, and note the position of the heart. 

2. Cut along the other side of the breastbone and note 
the thin partition, the mediastinum, attached to its 
inner surface. Cut the hinder end of the breastbone 
loose and raise it ; sever its attachment within and 
turn it forward. Observe the collapsed lungs on 
either side. Examine the anterior surface of the 
diaphragm. 



132 PRACTICAL ZOOLOGY. 

3. Note that the heart is, normally, in the plane of the 
mediastinum, and that this membrane entirely sepa- 
rates the two halves of the chest. 

4. Take the heart between the thumb and finger to feel 
how easily it slips about in its sac, the pericardium. 

5. Cut away the mediastinum and the pericardium, and 
note the appendages, auricles, at the large end, or 
base, of the heart. 

6. Cut away the breastbone entirely, press the ribs out 
to the sides, and dissect away a thin layer of muscles 
covering the windpipe, so that the blood-vessels which 
run forward from the heart into the neck may be 
traced. Carefully pick away a fatty-looking body, 
the thymus gland, in front of the heart and trace the 
following arteries. 

7. The main artery, the aorta, is a whitish, thick-walled 
tube. Springing forward from the centre of the base 
of the heart, it soon arches over to the left (of the 
animal) and runs along the middle of the dorsal wall 
of the chest-cavity, piercing the diaphragm, as noted 
in studying the abdominal cavity. 

8. At the arch the aorta gives off two branches ; the 
first of these soon subdivides, giving off a branch to 
the right fore limb, the right subclavian artery, a 
branch running along each side of the windpipe, the 
right and left common carotid arteries (called com- 
mon because each as it nears the head divides into 
the internal carotid and the external carotid). The 
second branch from the arch is the left subclavian 
artery. 

9. Just outside of the common carotids on each side are 
the white, thread-like pneumogastric nerves. 



THE BABBIT. 133 

10. Observe on each side of the neck the dark jugular 
ye in running back toward the heart ; note that each 
of these is formed by two main branches, the external 
and internal jugular veins, which unite just back of 
the head. 

11. Just before each jugular vein enters the chest-cavity 
it receives a branch from the corresponding fore 
limb; these are the subclavian veins. The union of 
the jugular and subclavian veins on each side forms 
the vena cava superior. 

12. Trace the right vena cava superior straight back to 
the right auricle. Turn the heart forward and follow 
the course of the left vena cava superior in reaching 
the same auricle. 

13. The large vena cava inferior, coming forward through 
the diaphragm to the right auricle, is easily seen. 

The heart and lungs may now be removed, and the 
pulmonary artery and veins traced, and the structure 
and action of the heart made out by the following 
directions ; but the heart and lungs of the pig, calf, 
or sheep will show the same features much better on 
account of their greater size. 

THE HEAD OF THE RABBIT. 

Remove the skin from the head. 
1. Below and back of the ear is an irregular pink mass, 
the parotid salivary gland. The duct which con- 
veys its secretion runs forward and opens on the 
inside of the cheek. It is hard to trace in the rabbit. 
Find it in the dog, slit into it with fine scissors, and 
push a bristle forward through it to find its opening 
in the mouth. 



184 PRACTICAL ZOOLOGY. 

2. Note the branches of the facial nerve running up- 
ward over the cheek. Dissect away the parotid gland, 
and find where the facial nerve emerges from the skull. 

3. In the angle between the two branches of the lower 
jaw observe two roundish bodies, the submaxillary 
salivary glands- In the dog trace their ducts as in 
the case of the parotid. 

4. Observe the muscle which covers the outside of the 
back part of each lower jaw. This is the masseter 
muscle. Place the fingers on the angle of your own 
jaw and note the action of the masseter muscle in 
shutting the teeth firmly together. In the rabbit 
note the attachment of the masseter to the under edge 
of the cheekbone. Trim the muscle entirely away. 

5. After removing the submaxillary glands, a muscle 
will be found on each side having its origin on the 
inside of each half-jaw near their junction. These 
are the digastric muscles; they depress the lower 
jaw. Cut away all the muscles and other connec- 
tions and remove the whole of the lower jaw. 

6. Carefully examine the tongue. 

7. Thoroughly clean the lower jaw and examine the 
teeth. How is the lower jaw hinged to the skull, and 
what motion does this hinge allow? How does the 
rabbit move its lower jaw? What is the relation 
between this jaw-motion and the direction of the 
ridges on the grinding teeth, or molars? 

8. Observe the opening on the inner surface of each 
half-jaw where the nerve entered to supply the teeth. 

9. Look at the side of the back part of the mouth for an 
opening leading toward the ear, the Eustachian tube. 

10. Trace the nasal passages. 



THE RABBIT. 135 

THE LEGS OF THE RABBIT. 

Most of the following structures may be made out from 
a shinbone of a sheep, readily obtained from the butcher. 

1. After removing the skin from the legs, observe the 
muscles, covered by a thin glistening membrane, the 
muscle-sheath. Study the shape of the muscles. 

2. Note the white tendons which terminate the muscles. 

Loosen the tendons from surrounding tissues and 
separate the muscles from each other along their 
sides without cutting them. Pull the different mus- 
cles to determine the motion each produces. 

A muscle which straightens a limb is an extensor. 

A muscle which bends a limb is a flexor. 

3. The large tendon running along the back side of the 
shinbone is the tendo Achillis; it corresponds to 
what part of our bodies? to what part of the horse? 

4. By further dissection find how the different move- 
ments of the toes are effected. 

5. Cut into the knee-joint. Observe the liquid, the 
synovia, which oils the joint. Rub a drop of it be- 
tween the thumb and finger. 

6. Observe the glistening bands which hold the ends of 
the bones together. These are the ligaments. Care- 
fully study their arrangement and uses. 

7. Note the thin layer of cartilage over the ends of the 
bones. Feel of it. Cut it. What are its properties, 
and what its uses ? 

8. With the forceps strip off a little of the muscle- 
sheath from one of the muscles and note the color of 
the latter. Cut one of the muscles across in its mid- 
dle and examine the cross-section. Each fibre lias its 



136 PRACTICAL ZOOLOGY. 

own thin sheath, and the small bundles of fibres have 
separate sheaths, which make the white markings seen 
in chipped dried beef. 
9. Tear off a few fine fibres of the muscle, mount on a 
slide in water, or glycerine, cover with a cover-slip, and 
examine first with a low and then with a high power. 
The fine cross-markings of the fibres give to this kind 
of muscle the name of striped, or striated, muscle. 
10. Thoroughly clean one of the long bones and make a 
drawing of it. Saw it in two lengthwise and make a 
drawing of the surface thus exposed. Put a bone into 
weak acid, and after a day or two compare it with an- 
other, that has been burned. 

For a more complete guide to the study of the rab- 
bit, consult Parker's " Zootomy " ; and " Practical 
Physiology," Foster and Langley. 



THE HEART AND LUNGS 

OF PIG, SHEEP, OR CALF. 

Get the heart and lungs entire as first removed from the 
body and "cut long," the "pluck," as the butchers call it. 

1. Hold the mass up by the windpipe, with the heart 
toward you ; you now look at the front of the heart 
as it hangs between the lungs. 

2. Observe the windpipe, or trachea, with its stiff rings 
of gristle, or cartilage. 

3. Back of the windpipe is a soft red tube, the gullet; 
find where it is cut off below, or cut across it, and note 
its whitish lining, the mucous coat. The thick red 



HEART A^D LUNGS OF MAMMAL. 137 

coat is the muscular coat; try to make out an inner 
layer of circularly arranged fibres and an outer longi- 
tudinal layer. 

4. Separate the gullet and windpipe and compare the 
front and back surfaces of the latter ; cut across the 
windpipe and make out the shape of the rings of 
cartilage. 

5. Observe the smooth rounded posterior surfaces of the 
lungs which were fitted against the ribs on each side 
of the spinal column. 

6. Lay the lungs on the table, with their posterior sur- 
faces down, and with the point of the heart extending 
away from you. The surface of the heart now upper- 
most is its anterior surface, the side to your right is its 
right side, and its left side is to your left. The point 
of the heart is its apex, and the large end is its base. 

7. If the sac which surrounds the heart, the pericardium, 
be not already cut away, note how easily the heart 
moves about in it, and then slit it along its anterior 
surface. Observe the pericardial fluid. 

8. Carefully compare the right and left sides of the 
heart. Observe a groove running obliquely along the 
anterior surface of the heart in which run blood-ves- 
sels, often covered by fat. The part to the right of 
this groove is the right ventricle; the part to its left 
is the left ventricle. Press the two sides and note 
the difference in firmness. 

9. At the base of the heart, on each side, find an ear-like 
appendage, with notched margins ; these are the right 
and left auricles. 

10. Seize the apex of the heart and tip it up toward you. 
Compare the front and back surfaces of the heart. 
Compare the thickness of the heart from right to left 



138 PRACTICAL ZOOLOGY. 

and from front to back. Hold the heart between the 
two hands, with its apex up, and again compare the 
firmness of the two ventricles. 

11. Turn the heart to the left and examine the right auri- 
cle ; find a large, red-walled tube entering it from the 
front; this is the superior vena cava, which brings 
the blood from the head, neck, and fore limbs to the 
right auricle. Trace this vein forward to the point 
where it was severed (or if this is not readily found, 
prick a hole in it) ; insert the point of the blowpipe, 
pinching the vein closely about it, and inflate the 
vein. Meanwhile watch closely the posterior part of 
the auricle ; there should be discovered another tube 
entering the auricle from behind, the vena cava infe- 
rior, which passes forward through the diaphragm ; 
find where it was severed, and inflate the right auricle 
through it, holding the vena cava superior if neces- 
sary. By this inflation the outlines of the right auri- 
cle and ventricle should be determined. 

12. Turn the heart to the right and observe a large, light- 
colored tube arising from the base of the right ventri- 
cle between the two auricles; this is the pulmonary 
artery \ again turn the heart to the left and raise the 
right auricle ; find a second large artery arising from 
the center of the base of the heart ; this is the main 
artery, or aorta. Carefully separate the aorta and 
pulmonary artery above the base of the heart. 

13. Trace the aorta as it arches over and runs down 
between the two lungs behind, alongside the gullet ; 
find where it was cut off. With knife and scissors 
cautiously clear away the whole arch of the aorta 
from the surrounding tissues. 

14. From the arch of the aorta arise the branch or 



HEART AND LUNGS OF MAMMAL. 139 

branches which supply the head and fore limbs. 
Compare the branches, as here found, with those of 
the rabbit's aorta, and of the human aorta as shown 
by the cuts in any text-book of human anatomy and 
physiology. 

15. Now trace the pulmonary artery and its two branches 
as they subdivide to the right and left lungs. 

16. Follow the branches, the bronchi, of the windpipe to 
the lungs. Follow one bronchus as it is distributed 
through the lung. Observe the structure of the lung. 
Cut a lung in two, and on the cut surface find the 
flabby ends of the blood-vessels and the stiff ends of 
the branches of the bronchi. With a probe trace the 
latter back to the trachea. 

17. Try to distinguish the pulmonary veins ; those from 
the right lung run close along the right auricle on 
their way to the left auricle. 

18. Cut the pulmonary arteries and veins near the lungs, 
trim away the pericardium close to the heart, and 
keep the heart in a cool place for further study. 

THE STRUCTURE AND ACTION OF THE HEART. 

1. Make three full-size drawings of the heart, front 
view, back view, and side view, naming the parts and 
blood-vessels as given above. 

2. With scissors slit down the vena cava superior, and 
continue the cut across the back of the right auricle, 
and for a short distance along the back of the vena 
cava inferior. Explore the cavity of the right auricle. 
Opposite the entrance of the vena cava inferior ob- 
serve, in the red inner wall of the auricle, a rounded 
depression, the fossa oval is, across the bottom of 



140 PRACTICAL ZOOLOGY. 

which is stretched a paler membrane ; by slight pres- 
sure with the handle of the forceps, prove that this 
membrane is thin and yielding. Below the fossa ova- 
lis is the opening of the azygos vein. With a 
syringe inject water into it and find whence it comes. 
The projection between the entrance of this vein 
and the fossa ovalis is the Eustachian valve- With 
scissors slit open the azygos vein and find, entering 
it, veins from the walls of the heart. Trace these 
veins. 

3. Cut away the whole of the right auricle; hold the 
heart in the left hand, with the left ventricle resting 
against the palm ; pour water suddenly from a consid- 
erable height into the right ventricle, watching closely 
to see the valves float up and separate the auricle 
from the ventricle. Pour in water again, and as soon 
as the valves rise, press with the fingers on the outside 
of the right ventricle ; note the effect of this pressure. 
Where does the water escape ? 

4. Empty the heart and examine the valves which have 
been seen ; they will now be found lying close against 
the walls of the ventricle. Note the white cords 
attached to the lower edges of these valves. 

5. Push a finger past these valves to the very bottom of 
the ventricle ; from the outside cut through the wall 
of the ventricle at this point, and cut cautiously 
upward along the border of the cavity of the right 
ventricle. Raise the outer wall of the ventricle and 
more thoroughly study the valves ; slip a blunt instru- 
ment between the flaps of the valves and the walls 
to which they adhere, and raise them so they can be 
better seen. How many flaps are there, and how are 



HEART AND LUNGS OF MAMMAL. 141 

they arranged ? How are they held in place ? How 
are they acted upon, and how do they act? 
Find the connection between the right ventricle and 
the pulmonary artery. Cut away the wall of the 
right ventricle so that the beginning of the pulmo- 
nary artery may be seen from below. Hold the heart 
up by the pulmonary artery and force a stream of 
water through the pulmonary artery toward the 
heart. Look from beneath to see the filling and 
bulging out of the valves at the beginning of the 
artery. Note the number, shape, and arrangement of 
these valves. What is the effect of the stream of 
water on them, and what is their effect on the stream 
of water? Slit the artery and examine the valves 
from above. These are the semilunar valves. 
Examine the left auricle to find where the pulmonary 
veins enter it ; cut the auricle away from the ventri- 
cle and examine it from the inside to see the openings 
of the pulmonary veins. Pour water into this ventri- 
cle as with the right. Compare the valves of this 
and the right side of the heart. 

Cut off the aorta near the heart; watch the open- 
ing of the aorta when water is poured into the ven- 
tricle, to see the action of the valves. In the pockets 
of the valves of the aorta look for the openings of 
the arteries which supply the walls of the heart with 
blood. 

Cut open the left ventricle and compare its walls 
with those of the right ventricle. Why are they dif- 
ferent? Note the partition between the ventricles ; is 
there any direct communication between the right 
and left halves of the heart ? 



142 PRACTICAL ZOOLOGY. 



THE VALVES IN THE VEINS. 

Dissect back the skin from the throat of the rabbit, cat, 
or dog, till the jugular veins are well exposed. Let the 
head of the animal hang over the edge of the table ; note 
that as the blood presses back toward the head it causes 
marked bulging at certain points ; with the handle of the 
forceps slightly stroke the vein toward the head, watching 
the bulgings. Dissect out the jugular vein from the head 
to the shoulder ; insert the nozzle of a syringe, first into 
one end and then into the other, and show the effect of 
forcing currents in each direction. Cut the vein open 
along one side, pin inside out to a piece of a shingle and 
examine the thin pocket-like valves. Test the elasticity 
of the vein. Note the smoothness of its inner coat. 
Remove a piece of an artery and experiment in the same 
way with it. 

DEMONSTRATION OF THE ACTION OF THE HEART. 

Get the heart and lungs entire. Dissect out the aorta 
as before. Clear the pulmonary artery and cut off both 
branches close to the lungs. Carefully trim away the 
pericardium and clean the venae cavse inferior and supe- 
rior. Turn the heart back and find one of the larger 
pulmonary veins ; cut a hole in it near the lung and slip a 
glass tube into it toward the heart ; this tube should have 
a groove, made by drawing it out in the flame ; tie the 
tube firmly in, and ligature the other pulmonary veins 
without stopping to trace them. Tie any and all connect- 
ions with the heart now remaining and cut beyond the 
ligatures. Get a retort-stand and two large glass funnels. 



HEART AND LUNGS OF MAMMAL. 143 

Place the funnels in the rings. Lay the heart, now 
wholly severed from the lungs, on its front surface. Con- 
nect one funnel, by rubber and glass tubing, with the left 
auricle by the tube already in the pulmonary vein ; con- 
nect the other funnel with the right auricle through the 
vena cava superior; ligature the vena cava inferior. Lay 
the heart in a basin and pour water into the funnels ; hold 
the heart with the two hands and compress it, repeatedly 
adding water. In this way the clotted blood usually 
present in the right ventricle may be washed out. If 
this remain, it may interfere with later experiment. Con- 
nect the aorta with the funnel which leads to the right 
auricle, by means of a glass tube which bends over the 
edge of the funnel, thus holding itself in place by the 
hook, and emptying into this funnel any liquid which 
escapes from the tube. 

In like manner have a bent glass tube, from the pul- 
monary artery, hooked over the edge of the funnel leading 
to the left auricle. 

Pour water into one of the funnels and compress the 
heart to imitate its natural contraction ; observe where 
the liquid next appears ; add more water and follow it 
around to its starting-point. A little ink may be poured 
into one of the funnels and traced around, as the heart is 
worked, to its starting-point. 

That there is no direct connection between the two 
halves of the heart may be shown by letting the liquid 
from each artery empty into the auricle of the same side 
of the heart. Different colored liquids may be used in the 
two funnels. 



144 PRACTICAL ZOOLOGY. 



THE MUSCLES OF THE EYEBALL. 

With bone-forceps, or a strong knife, cut away the bone 
at the outer angle of the eye-socket of the rabbit (almost 
any mammal will serve for this, though the bone is so 
thick in the calf or sheep that it will be difficult work 
without the aid of a good pair of bone-forceps). 

1. With scissors trim away the white membrane around 
the front of the white of the eye ; this was continuous 
with the lining of the eyelid, and is the conjunc- 
tiva. 

2. Find a muscle running along the roof of the eye- 
socket, which passes through a loop of tendon, near 
the edge of the orbit, and turns outward to its attach- 
ment to the top of the eyeball. This is the superior 
oblique muscle. 

3. Beneath the eye find a muscle, having its origin in 
the inner front part of the socket, and passing out- 
ward to be inserted in the lower surface of the eye- 
ball; this is the inferior oblique muscle. 

4. Four straight muscles, the inferior, superior, internal, 
and external recti, are attached to the top, bottom, 
and sides of the eyeball ; find the origin of these, with 
that of the superior oblique, at the posterior extrem- 
ity of the eye-socket. 

5. Dissect away the fat and other tissue around these 
muscles, and find a cone-shaped muscle attached to 
the back of the eye. Within this find the cylindrical 
optic nerve. 



THE EYE. 145 



EXTERNAL PARTS OF THE EYE. 

The eye of the rabbit may be used, but that of the ox is 
better. 

1. Observe the clear front part of the eye, the cornea. 
Note its shape. Its wider end was at the inner angle 
of the eyelids. 

2. Around the cornea find a whitish membrane, the 
conjunctiva, which a short distance back from the 
cornea separates from the eyeball to turn forward 
and line the eyelid. 

3. The severed muscles of the eyeball, a mass of fat 
which forms a cushion for the eye, and other tissue, 
should be trimmed away leaving the optic nerve, 
which enters the eye below and outside of the centre 
of its posterior surface ; the place of entrance of the 
optic nerve, together with the shape and natural 
position of the cornea, will serve to distinguish the 
right and left eyes. 

4. Place the eye in its natural position, and make draw- 
ings of it as seen from the front, from behind, being 
still careful to have it right side up, and from one 
side, naming the parts, and stating whether it be the 
right or the left eye. 

DISSECTION OF THE EYE. 

1. Lay the eye on a plate with the cornea uppermost. 
Hold the eye firmly with the thumb and fingers of 
one hand ; with the thumb and forefinger of the 
other hand hold one blade of the scissors half an 
inch from its tip; with a steady motion push the 
blade horizontally through the cornea near its edge. 



146 PRACTICAL ZOOLOGY. 

2. The liquid in the cavity back of the cornea is the 
aqueous humor. 

3. Cut around the margin of the cornea and remove it. 

4. The dark membrane now exposed is the iris. Pinch 
the eye slightly at the sides to make the iris show 
more distinctly. The hole in its centre is the pupil. 
With the forceps raise the edge of the iris around 
the margin of the pupil to see that it is here unat- 
tached to the structures underneath. Observe the 
color and markings of the iris. 

5. From one end of the pupil cut outward to the outer 
margin of the iris, then cut around its outer margin 
and remove it. Observe the color and markings of 
its posterior surface. 

6. The body now laid bare is the crystalline lens. Touch 
it. 

7. With a sharp knife make a quick light gash across 
the surface of the lens to cut through the thin coat 
which envelops it, the lens capsule. Enlarge the 
opening thus made and carefully pry out the lens 
with the handle of the forceps, noting closely, in so 
doing, the difference between the front and back sur- 
faces. Lay the lens on a piece of newspaper and look 
through it at the letters. Make a drawing of the lens 
as seen from the front, and as seen from one side, 
naming the front and back surfaces. 

8. With the forceps seize the lens capsule where it was 
cut and pull it gently but firmly to one side ; this 
action will probably tear the mass within the eye 
loose from the outer coats ; repeat the pull in all 
directions. With the scissors now cut outward about 
one-fourth of an inch from the edge of the hole made 



THE EYE. 147 

in the front of the eye ; then cut clear around the eye 
and remove a strip of this width, thus enlarging the 
opening before made. On the inside of the strip 
removed there may be found radiating black ridges, 
the ciliary processes. Note part of these ciliary 
processes around the margin of the lens capsule. 
9. Carefully pick away with the forceps and snip away 
with the scissors everything on the surface of the 
clear mass beneath. 

10. The substance filling the remainder of the eye-cavity 
is the vitreous humor. 

11. Through the vitreous humor the entrance of the optic 
nerve may be seen with the blood-vessels radiating 
from it. 

12. The tough outer coat of the eye is the sclerotic coat. 

13. Inside the sclerotic is the dark choroid coat. 

14. The inner, nearly transparent coat is the retina. 

15. Drag out the vitreous humor and note the soft whit- 
ish retina ; observe that it is a continuation of the 
optic nerve. Tear away the retina, noting its con- 
sistency. Note the color and luster of the inner sur- 
face of the choroid coat. 

The reflection of light from this surface of the 
choroid coat causes the color seen in the eyes of some 
animals. Turn the remaining coats inside out and 
tear the choroid coat from the sclerotic. Observe the 
blood-vessels passing from one to the other. 

THE LARYNX OF THE CALF. 

1. The front of the larynx is readily distinguished by the 
projection of cartilage known as the Adam's apple. 



148 PRACTICAL ZOOLOGY. 

2. Along the back of the larynx runs a thick muscular 
tube, the guilet, with a white lining membrane. 

3. Trim away the muscles and other tissues from the 
front and sides of the larynx. The large cartilage 
forming the greater part of the front of the larynx is 
the thyroid cartilage. 

4. Observe the band of muscle attached to either side of 
the thyroid cartilage and passing horizontally back 
around the esophagus. 

Cut away this muscle as completely as possible and 
entirely remove the gullet. Note that the whitish or 
yellowish mucous membrane which lines the gullet 
is continuous with the lining of the larynx. Study 
now more fully the shape of the thyroid cartilage. 

5. Back of the upper part of the thyroid cartilage, cov- 
ering the upper end of the larynx, is the arched 
epiglottis. Feel of it to learn its consistency. Press 
it upward and forward, then downward and back- 
ward ; observe that it now covers the entrance to the 
larynx ; note the position it takes when released. 

6. Just back of the upper angle of the thyroid cartilage 
find a muscle connected with the base of the epiglot- 
tis ; pull this muscle to determine what effect its 
contraction produces on the epiglottis. 

7. Under the thyroid cartilage in front observe a narrow 
ring of cartilage not much wider than one of the rings 
of the trachea. Move this up and down to prove that 
it is distinct from the thyroid. This is the cricoid 
cartilage. 

8. Observe the sheet of muscle passing from the cricoid 
to the thyroid. Again move the cricoid toward and 
from the thyroid ; what does this muscle do ? Cut 



THE LARYNX. 149 

away this muscle from one side and see that the cri- 
coid cartilage widens as it passes backward. How are 
the cricoid and thyroid hinged together ? 
9. Projecting upward and backward from the top of the 
larynx are two curved yellowish cartilages, the aryte- 
noid cartilages. Move them about to see that they 
are movable and that they rest on the upper edge of 
the back part of the cricoid cartilage. 

10. With one hand move the arytenoid cartilages back- 
ward and forward, meanwhile watching the inside of 
the larynx from its lower opening. The projecting 
ridges, which meet just back of the Adam's apple, are 
the vocal cords. What effect is produced on the 
vocal cords by the movements of the arytenoid carti- 
lages ? 

11. Observe the connection of the thyroid cartilage with 
the cricoid by means of a downward projection of the 
former. Cut away all of this half of the thyroid 
cartilage. Notice the slender hyoid bone loosely 
connected with the upper bone of the thyroid. 

12. Examine now the muscles which move the arytenoid 
cartilages. 

a. On each side of the posterior surface of the cri- 
coid is a muscle passing upward to be attached to 
the corresponding arytenoid; this is the poste- 
rior crico-arytenoid muscle. Dissect it loose 
from the cricoid, at its origin below. By pulling, 
determine its action on the arytenoid, and through 
the arytenoid on the vocal cord. 

J. Arising from the upper edge of the side of the 
cricoid cartilage, and passing upward and back- 
ward to the arytenoid, is the lateral crico-aryte- 



150 PRACTICAL ZOOLOGY. 

noid muscle; cut away at its origin close to the 
cricoid and demonstrate its action on the aryte- 
noid cartilage and vocal cord. 

c. A broad muscle arising along the whole length of 
the angle of the cricoid, whose fibers converge to 
the arytenoid cartilage. This is the thyroaryte- 
noid muscle; cut it across near its origin, dis- 
sect it loose, and by pulling it toward its origin 
prove its action. 

d. On the posterior surfaces of the arytenoids is the 
small arytenoid muscle. 

13. Cut between the arytenoid cartilages and remove one 
of them. Examine the joint between the arytenoid 
and cricoid. Note the synovia lubricating the joint. 

Trim away the muscle from the arytenoid cartilage 
and study the shape more fully. Fit it again to its 
place and recall the motions given by each muscle. 

14. Now examine the arj^tenoid cartilage and the vocal 
cord of the opposite side ; move the arytenoid back 
and forth, watching the vocal cord. 

15. Remove the epiglottis and cut into it to see its 
structure. 

16. Dissect away the parts of the other side from the 
inside, reviewing the above points. 



THE STARFISH. 

For this work there is needed : — 
1. A set of dried specimens, one for each student ; such 
a set may be used with successive classes and will last 
for years if carefully handled and kept in a dry place. 



THE STARFISH. 151 

2. Alcoholic specimens for dissection. 

3. It is desirable to have a set of prepared slides, 
showing cross-sections of a decalcified ray of a young 
starfish, and a ground-down section of a calcarecrus 
plate, etc. 

4. An injected starfish and a number of injected rays. 

The above and other desired material for work on ma- 
rine animals may be obtained of Mr. B. H. Van Vleck, 
Boston Society of Natural History, Boston, Mass. 

DEIED SPECIMEN. 

1. Observe, first, the shape of the body as a whole. The 
central portion is the disk and its radiating extensions 
are the arms, or rays. Note that the rays are bilater- 
ally symmetrical. 

2. The mouth is at the center of a thin membrane in the 
middle of the oral surface; the opposite surface is 
called aboral. 

3. Cut into one of the rays. Observe that the body 
cavity is bounded by a leathery wall in which are im- 
bedded hard plates. Compare a piece of a ray of an 
alcoholic specimen with the dried one. 

4. Test the flexibility of the integument of the alcoholic 
specimen. By picking with forceps, prove that there 
is soft matter, both on the outside and on the inside 
of the hard plates. To show the real nature of the 
plates and their relation to the integument, proceed 
as follows : — 

a. Handle a starfish which has been decalcified, i.e. 
has had its calcareous matter removed by very 
weak (two per cent) nitric acid, chromic or other 



152 PRACTICAL ZOOLOGY. 

acid. Observe that the body wall is still present 
but lacks the hard parts. 

b. Examine a microscopic section of a decalcified ray 

of a young starfish; in such section it should be 
more clearly seen that the calcareous plates are 
wholly within the integument. 

c. To show still further the relation between the 

plates and the integument, prepare a thin section 
of a calcareous plate, as follows : select some pieces 
of a starfish (left from previous dissection). Boil 
a few of the larger plates in caustic potash in order 
to remove all the organic matter; wash, and when 
thoroughly dry, smooth down one side on a fine 
file; polish on a perfectly clean oil-stone; cement 
this surface of the plate to a glass slide by means 
of a drop of Canada balsam which has been boiled 
on the slide, until on becoming cold it is with 
difficulty indented by the thumb-nail. Proceed 
then to plane off, by means of a file, and when 
quite thin, scrape carefully with a sharp knife, 
finally smoothing it on an oil-stone. The speci- 
men should be examined from time to time under 
the microscope, in order to ascertain when the 
proper degree of thinness has been reached. Dis- 
solve the balsam by means of turpentine, or better, 
if properly managed, melt the balsam over a lamp 
and carefully push the section into a watch-crys- 
tal containing turpentine ; when thoroughly freed 
from balsam, carefully brush it with a camel's- 
hair brush and mount in Canada balsam in the 
ordinary manner. 
5. Observe the arrangement of the plates and spines in 



THE STARFISH. 158 

different regions of the body wall. Along the middle 
of the oral surface of each ray may be seen the 
shrivelled remains of the tube feet, or ambulacra. 
The region in which they lie is the ambulacral area. 
The plates along this tract are the ambulacral plates. 
One row of plates on each side of these ambulacral 
plates are known as the inter-ambulacral plates. Ex- 
amine these closely for comparison with the sea-urchin. 

6. The wart-like elevation on the aboral surface is the 
madreporic body. Note that it is situated opposite 
one of the inter-radial angles. Examine it with a lens. 

7. Make drawings of the oral and aboral surfaces of the 
starfish. 

ALCOHOLIC SPECIMEN. 

1. Briefly review the points noticed in examining the 
dried specimen. Bend the rays; their flexibility is 
now much less than in life. 

2. Compare the spines of different areas as to their shape, 
size, and degree of mobility. 

3. Between the spines are soft, tapering projections, the 
aboral tentacles. 

4. Observe a circle of projections surrounding the spines ; 
delicately pinch them with the forceps to determine 
their consistence ; remove some of these bodies to 
strong alcohol; mount temporarily in turpentine on a 
slide, cover, and examine with a low power. There 
should be distinguished a short stalk bearing a pair of 
pinchers; these bodies are the pedicellariae. In the 
live starfish these pinchers may be seen continually 
snapping; they are supposed to serve in removing 
foreign matter from the body. 



154 PRACTICAL ZOOLOGY. 

5. The soft cylindrical projections along the median tract 
of the oral surface of each ray, are the ambulacra or 
tube feet. Remove one of them and examine it with 
care. Note the arrangement of the series. 

6. Press apart the tube feet and find running along the 
median line of the ambulacral groove, a yellowish or 
whitish ridge, the nerve of the ray. Trace it to the 
soft membrane bordering the mouth, the peristome, 
and find the nerve ring around the mouth. 

7. Trace the nerves also to their outer ends and find a 
reddish or yellowish elevation, the eye-spot, borne at 
the base of a median terminal tentacle, resembling a 
tube foot. 

8. The eye-spot is borne on a distinct, but minute, plate. 
Compare j r oung and old specimens to see that what- 
ever the size, this single ocular plate with its eye-spot 
is always at the end of the ray. Count the ambula- 
cral plates in a short and in a long ray. Where do the 
new plates develop ? 

DISSECTION OF THE STARFISH. 

1. The ray opposite the madreporic body is the anterior 
ray- Cut through its aboral wall near the outer end, 
and from this point cut along the upper part of each 
side of the ray, an inch or two toward the disk ; raise 
the flap thus freed, and, avoiding internal organs, 
continue the cut on each side to the disk. 

2. Attached to the aboral wall find a pair of elongated, 
branched bodies, the hepatic caeca. Note how each 
caecum is held in place by the thin mesentery. 

3. Along the middle line of the aboral wall, inside, is a 
yellowish streak, the extensor muscle of the ray; 
with forceps prove its general structure. 



THE STARFISH. 155 

4. Along each side of the ridge in the floor of the ray, 
observe rows of thin-walled sacs, sometimes distended, 
but more often collapsed in alcoholic specimens. 
These are the ampullae, or ambulacral vesicles. 
Watch the ampullae while pressing on the tube feet, 
and vice versa. If a specimen injected with coloring 
matter be at hand it should now be examined. 

5. Near the base of the ray find, on each side, an elon- 
gated body resembling a bunch of grapes, and of a 
lighter color than the caeca; these are the reproduc- 
tive bodies and are very much alike in appearance in 
the two sexes, and only distinguishable by color or by 
microscopic examination in the living specimens. Find 
the point of attachment of one of them. The open- 
ings in the inter-radial angle are not very evident. 

6. Cut along the sides of the two rays lying on the right 
and left of the anterior ra}% connect the cuts at the 
inter-radial angles, and turn back the cover of the 
three rays and disk. Within the disk is the large, 
thin-walled stomach. Examine this organ carefully. 
Pass a blunt probe through the mouth and explore 
its interior. 

7. Observe the large lobes of the stomach extending a 
short distance into the rays ; lift one of these lobes 
and trace the thin retractor muscles of the stomach 
to the sides of the ridge in the ray. 

In the live starfish the stomach is often found pro- 
truded and surrounding a mussel or an oyster; after 
digesting and absorbing its soft parts the stomach is 
retracted. 

8. Turning to the caeca of the anterior ray, trace them 
toward the stomach: find the union of their tubes 



156 PRACTICAL ZOOLOGY. 

and the entrance of their common duct into the 
stomach. Observe the place where this tube enters 
the stomach, in reference to the corresponding lobe 
of the latter. 

Carefully cut the mesentery along the aboral wall 
and wholly free the caeca of this ray from all attach- 
ment above. Xote that the mesentery is double. 
9. Hold the starfish inverted and pour water through 
the mouth into the stomach to show its shape. 

10. In the other two rays which have been opened, cut 
across the common ducts of the caeca close to the 
stomach, and leave them attached to the aboral walls. 

11. Find the extremely short intestine connecting the 
stomach with the upper wall of the disk, near the 
junction of the extensor muscles of the rays. Find, 
also, some small branched appendages of the intestine. 
The anal opening is minute. 

12. Sever the intestine close to the aboral wall, cut across 
the disk close to the madreporic body, and remove 
entirely the roof of the disk and the three rays. 

Make a drawing of the organs now exposed, show- 
ing the caeca in one ray, the reproductive bodies in 
another, and the ampullae in the third. 

13. Thoroughly examine the stomach, and remove it after 
cutting across the short esophagus. 

14. The S-shaped stone canal may now be seen passing 
downward from beneath the madreporic body. 

15. Traced to its lower end, the stone canal may be found 
to enter a membranous hollow ring, whose outer bor- 
der rests against the inner surface of the hard parts 
surrounding the mouth ; this tube is the circum-oral 
water-ring. Connected with its inner surface, find 



THE STAKFISH. 157 

several pairs of pouches, which in the contracted 
state are mere button-like projections. How many of 
these are there, and are they all in pairs ? 

Observe also the pouches, like ampullae, connected 
with the upper part of the hard ring around the 
mouth. Press on the water-ring at the level of the 
peristome, and watch the effect of this action on these 
last-named pouches or vesicles. Is there any connec- 
tion between them and the water-ring ? 

16. Enclosing the stone canal is a thin membrane, the 
pericardium. Carefully tear it away. Alongside 
the stone canal is a soft tube, the heart. In the live 
starfish it may be seen to pulsate. 

17. Cut across the middle of a ray in two places, about 
an inch apart, and make a careful study of the part 
included between the cuts. Remove the hepatic 
caeca, observing again how they are suspended by the 
mesenteries. Cut through the aboral wall in the 
middle line and spread open the ring. Observe the 
depressions in its inner surface ; in the bottoms of 
these depressions find small holes. What is the rela- 
tion between these holes and the nearest structures 
seen on the outside? 

18. Slowly peel away the thin membrane which lines the 
interior of the ray, noting especially the connection 
between this membrane and the depressions above 
noticed. Also watcli closely the aboral tentacles 
while tearing away this lining membrane. 

19. Turn now to the outside of the ray and gently scrape 
the surface. A thin layer here may also be easily re- 
moved. Thoroughly clean a small area, noting that 
the aboral tentacles come away with this layer. 



158 PRACTICAL ZOOLOGY. 

There will now remain a tough white layer in which 
are imbedded the calcareous plates which constitute 
the skeleton. Bend this membrane to see the relations 
of the calcareous plates to the membrane and to each 
other. 

20. By picking with the forceps prove that the membrane 
is continuous over both the inner and outer surfaces 
of the plates, as well as between them. This is an 
important point, as the calcareous plates are devel- 
oped in and by the membrane. 

Part of the membrane, if not all, has the power of 
contracting, by means of which motion is effected. 
Note the perforations in the membrane in its thinner 
portions between the plates where the aboral tenta- 
cles passed out. 

21. Reviewing what was noticed in the examination of 
the inner and outer membranes, it will be evident 
that the aboral tentacles are tubular extensions of the 
body formed by the protrusion of the inner mem- 
brane through the middle membrane, these tubes be- 
ing covered by the outer membrane. 

22. Turn now to the tube feet and their ampulla and 
make out their relations to each other and to the ad- 
jacent parts of the skeleton. The calcareous plates 
which form the sides of the ambulacral groove are 
the ambulacral plates. 

23. Pick away a few of the ampullae, and then the cor- 
responding tube feet, comparing the arrangement of 
the two. In this way clean the ambulacral plates 
and examine them carefully. 

24. Alternately press the ambulacral plates of the two 
sides together and separate them to see the range of 



THE STARFISH. 159 

motion allowed by the joint. Observe the muscles 
connecting the ambulacral plates of the opposite sides, 
just inside of the nerve. 

25. In the angle formed by the ambulacral plates, find the 
cut-off end of the water-tube of the ray. Insert in 
the end of this, the point of a drawn-out glass tube, 
and inflate. When the ampullae are distended, press 
on them with the finger and note the effect on the 
tube feet ; with a lens examine the distended ampullae. 
In fresh specimens the ampullae may be injected with 
a colored liquid or with gelatine to be kept as perma- 
nent preparations. In such preparations and in a 
microscopic section of a properly prepared ray, it may 
be seen that the water-tube of the ray sends off side 
branches to the tube feet, and also that the cavities of 
the tube feet and ampullae are continuous. By the 
contraction of the ampullae the tube feet are extended, 
and by the muscles in their walls they are moved from 
side to side and applied to the surfaces on which the 
starfish rests. The end is fixed by means of the sucker- 
like disk at the tip of the foot to some foreign object ; 
then by the contraction of the tube feet, the starfish 
pulls its body along. 

The water finds its way through the madreporic 
body into the stone canal, thence to the water-ring 
around the mouth, and from this to the radial canals. 
The water thus taken in probably serves for respira- 
tion as well as for locomotion. 

26. Make a drawing of a cross section of a ray, showing as 
many as possible of the above noted points of structure. 
A slide with a series of very small starfishes shows well 
how the rays are formed as outgrowths of the disk. 



160 PRACTICAL ZOOLOGY. 

For the anatomy and development of the starfish and 
sea-urchin, see Brooks' " Handbook of Invertebrate Zool- 
ogy," Hyatt's •" Common Corals, Hydroids and Echino- 
derms " (No. V. of " Guides for Science Teaching "), 
" Seaside Studies in Natural History," by E. C. and A. 
Agassiz, Romanes' " Jellyfish, Starfish, and Sea-Urchins " 
(Vol. XLIX. in the International Scientific Series). 



THE SEA-URCHIN. 

The requisites for this work are, cleaned skeletons, or 
tests, alcoholic specimens, microscopic sections, etc., as in 
the case of the starfish. 

THE CLEANED TEST. 

1. Observe the radial distribution of the parts around an 
axis, at one pole of which is a large opening. 

At the opposite pole is a circular area composed of 
several small plates, near the center of which is the 
anal opening. 

2. Note that the test is composed of distinct pieces or 
plates. Put one of the plates into a little dilute acid 
and note what occurs. 

3. To make out the real nature of the skeleton, proceed 
thus : — 

a. Handle an entire decalcified specimen, z.£., one 
from which the calcareous matter has been re- 
moved by chromic or other acid. Observe that 
the body walls and spines are still present. 



THE SEA-URCHIN. 161 

b. Examine a microscopic section of the decalcified 
body wall to see that there was soft living matter, 
both on the outside and on the inside of the cal- 
careous plates. 

c. Grind down and mount a thin section of a plate, 
as in the case of the starfish, and see that not 
only is the plate wholly enclosed in the body wall, 
but that it forms a network whose meshes were 
penetrated by the soft living substance of that 
body-wall. It should now be clear that the plates 
were formed by the deposition of calcareous mat- 
ter within the living tissues of the body wall. 
The joints, or sutures, between the plates are 
formed by the absence of the deposit of calcare- 
ous matter. 

4. Returning to the entire test, study the arrangement 
of the plates, their variations in shape, size, etc. 

Into how many similar areas may the surface of the 
test be divided? To make out these points, and the 
shapes of the plates, pull apart a piece of a dried test 
that was left over from previous dissection. 

5. At the aboral pole, observe a small distinctly marked- 
off area, including numerous small plates. This is 
the anal area, and the plates are the anal plates. 
Unlike the other plates, these, in the living sea-urchin, 
are movable. They surround the anus. 

6. Surrounding the anal area are the five large genital 
plates, each having a genital opening near its outer 
angle. 

7. With a lens examine the largest of the genital plates ; 
its perforated portion serves as a madreporic body. 

8. Radiating from the apex of each genital plate, is the 



162 PRACTICAL ZOOLOGY. 

zigzag inter-radial suture. How many kinds of 
plates are found within the area included by two 
adjacent inter-radial sutures? The perforated plates 
are the ambulacral plates, and the imperforated, the 
inter-ambuiacral plates. Compare these two sets of 
plates with the corresponding parts of a starfish. 
9. The ambulacral plates form the ambulacral areas. 
Trace each of the ambulacral areas to its aboral end, 
and find at its apex a small plate wedged in between 
two adjacent genital plates. These smaller ones are 
the ocular plates. Xote the small opening from 
which projects an unpaired tentacle, the end of the 
radial water-tube. 

10. Carefully compare the hard parts of the starfish and 
sea-urchin. Wherein are they alike, and wherein do 
they differ? What changes in growth would be 
necessary to convert one of these forms into the 
other? What part of a starfish is homologous with 
the anal area of a sea-urchin ? 

11. Make careful drawings of the oral surface, of the 
aboral surface, and of the side of the test. 

ALCOHOLIC SPECIMEN. 

For the sake of review and comparison, it is well to 
have the cleaned test before one in this study. 

1. Observe the soft membrane, the peristome, on the 
oral surface and the teeth projecting from the 
mouth. 

2. At the aboral pole look for the anus and genital 
plates. 

3. Examine one of the largest spines; move it about to 



THE SEA-URCHIN. 163 

see its range of motion. Remove it and make out 
how it is articulated to the test. The fleshy tube en- 
sheathing the base is muscular tissue, by the contrac- 
tion of which the spine is moved. Clean the spine 
and make a drawing of it. 

4. Note any variations in size and shape of the spines in 
various regions. 

5. Study carefully the arrangement of the spines, using 
the cleaned test for comparison. 

6. Between the spines in certain areas find soft tubular 
projections, the tube feet or ambulacra. In life they 
may be extended a considerable distance beyond the 
spines, being used for locomotion as in the starfish; 
carefully examine the tips of the tube feet to find 
what is therein contained. 

7. Find also among the spines and on the peristome, 
slender flexible stalks, bearing three-pronged pinch- 
ers. In life these pinchers keep opening and shutting. 

8. Pick away the spines and other projections prepara- 
tory to dissection, 

DISSECTION OF THE SEA-URCHIN. 

After removing the spines, cut, or better, saw with the 
blade of a metal saw, through the equator of the test; 
place under water and carefully raise the aboral portion 
at one side. 

1. Press on the tips of the teeth to show their connec- 
tion with the complicated apparatus known as the 
lantern; now open the test till the two halves are side 
by side and complete the dissection under water. 

2. Arising from the middle 1 of the inner surface of the 
lantern find the brown esophagus. Trace this as it 



164 PRACTICAL ZOOLOGY. 

passes in festoons about the body walls, widening to 
become the stomach. Trace the intestine to the anus, 
describing carefully its course. 

3. Pick away the alimentary canal from the oral half of 
the test. Note the five double rows of ampullae ; be- 
tween each of these double rows runs the radial 
water-tube, and between the water-tube and the test, 
is the radial nerve. 

4. In the aboral half, note the reproductive bodies in the 
loops of the intestine. Trace their ducts to the geni- 
tal pores. 

5. After cleaning away the intestine and reproductive 
bodies, trace the ampullae as they converge to the 
ocular plate. Compare the inside and outside of the 
test to see if the ampullae are really opposite the am- 
bulacra! pores noticed in the dry test. 

6. Study the lantern, make out how it is supported, and 
how its various parts are moved, and how they are 
used. 

Place in water the pieces of tests left after dissec- 
tion and macerate till the spines are readily detached. 
Then clean and keep them for the next class. They 
will be useful for pulling to pieces to make out the 
structure of the test. The sea-urchin and the star- 
fish may be taken as convenient types of the branch 
Echinodermata. To this group also belong the Brit- 
tle Stars, Holothurians, and Crinoids. 

THE DEVELOPMENT OF THE SEA-URCHIN. 

The reproductive bodies are very much alike in the 
two sexes, distinguishable only by color or by microscopic 
examination. 



THE SEA-URCHIN. 165 

In the dark-colored sea-urcliin (Arbacia punctulata) the 
ovaries are red, from the color of the contained eggs, 
while the testes are white. Through the genital open- 
ings already observed, there passes out into the water 
from the female a multitude of red spherical eggs. From 
the male there passes into the water a white liquid, which 
on examination with a high power of the microscope is 
seen to be composed of myriads of little bodies, the 
spermatozoa, like slender tadpoles, and swimming by the 
active vibration of their tails. 

If these two elements meet in the water the egg may 
be fertilized; otherwise, the egg does not develop, but 
soon dies. This process of the fertilization and the 
changes that the egg undergoes in consequence, have 
been studied in the following manner : — 

Live sea-urchins were opened, the ovaries and testes 
removed, and torn open to let their contents escape. The 
ova and spermatozoa were mixed in a watch crystal of sea 
water and watched under the microscope ; the actively 
swimming spermatozoa surround the ova; just how the 
fertilization is accomplished is not fully known ; it is 
believed that a spermatozoon enters the ovum. After this 
the egg mass contracts, leaving a clear space around it 
inside the outer coat, or cell wall; soon the egg mass 
within divides into two equal parts, each of these halves 
again divides into two, the four then become eight, six- 
teen, thirty-two, and so on till the number can no longer 
be counted and the egg looks like a spherical mulberry. 
This berry-like mass now becomes hollow, next one side is 
pushed in like a rubber ball with one side punched in ; 
on the outside are little hair-like projections of the cells, 
called cilia, which by their vibrations propel the body 



166 PRACTICAL ZOOLOGY. 

through the water. A set of needle-like rods develop 
within, which soon make a skeleton shaped somewhat like 
a common chair. This skeleton has a covering of soft 
tissue^ and the projections which correspond to the legs 
of the chair are covered with strong cilia for locomotion. 
The digestive tube has at first but one opening, that made 
by the doubling-in of the outer wall, as above mentioned, 
and the cavity of this depression forms the digestive 
cavity. The mouth is formed later by a new opening 
made through the outer wall into the first cavity and the 
original opening becomes the anus. So far the young sea- 
urchin is very unlike the adult; but after a time this larva 
begins to transform into the real sea-urchin, and soon the 
little sea-urchins, about the size of pins' heads, are found 
crawling up the sides of the glass vessels in which they 
are kept. 

The first of the changes here described should be care- 
fully remembered, as this division, or segmentation, of 
the egg is common to all but the very lowest animals, 
though the manner of division may greatly vary. 



THE FRESH-WATER HYDRA. 

The fresh-water hydra has a cylindrical body, varying in 
diameter from the size of a fine needle to that of a common 
pin, and from one-fourth to one-half an inch in length. It 
is found in fresh-water ponds and streams, usually attached 
by one end to submerged stems, leaves, etc., frequently 
on the under surface of a leaf. Surrounding the free end 
of the hydra is a circle of thread-like appendages, the 
tentacles, which often are longer than the body itself. 



THE FKESH-WATEB, HYDKA. 167 

Two species of hydras are found ; one green, the other 
brown or flesh-colored. Put the leaves and stems to 
which the hydras are attached into shallow dishes, such as 
fruit-dishes, and keep them in a light but shaded place ; 
watch their behavior when thus kept undisturbed. Cut 
off a bit of leaf bearing a hydra, and transfer it to a deep 
watch crystal half full of water. Without the aid of any 
lens watch the hydra for several minutes. When it is 
expanded, gently touch it with the tip of a pencil or other 
blunt object. 

Examine a hydra with a hand lens ; are all parts colored 
alike ? Place the watch crystal on the stage of a micro- 
scope and examine with a one-inch objective. The follow- 
ing points of structure should now be made out : — 

1. That the body is a hollow tube closed at one end and 
open at the other. This opening, within the circle of 
the tentacles, is the mouth. 

2. That the tentacles are also hollow tubes, closed at 
their outer ends, but at the inner communicating 
freely with the body cavity. 

3. That the body wall consists of two layers, which are 
continuous with the corresponding layers of the ten- 
tacles. How do these layers differ from each other? 

The body is, then, a double-walled sac, and the ten- 
tacles are simply extensions of this sac. Watch the 
movements of the different parts of the body. Can 
hydras move from place to place? If so, how is this 
accomplished? Look in the body cavity for foreign 
matter which lias been taken in through the mouth 
as food. Look also for minute particles obtained by 
the digestion of such food matter. These particles 
may often be seen in motion, caused by contractions 



168 PRACTICAL ZOOLOGY. 

of the body walls, or by the action of cilia lining the 
body cavity. Look for knob-like extensions of the 
side of the body. Buds are formed as outgrowths 
of the body walls with a cavity continuous with the 
body cavity. Place in a dish by itself with some 
aquatic plants, a hydra bearing buds, and watch from 
day to day the development of the bud into the form 
of the parent. Observe the free circulation of food 
material from the parent to the bud. Watch the 
formation of tentacles. Look also for a thinning 
away of the free end of the bud. 

What is the greatest number of buds found on any 
one specimen? Are buds borne on buds? By means 
of a pipette transfer a hydra in a large drop of water 
to a slide. Cut two strips of thick paper a quarter of 
an inch long and one-sixteenth of an inch wide and 
lay one on each side of the drop of water. Carefully 
place the coverslip on the water, with its edges rest- 
ing on the papers so as not to crush the specimen. 

Examine now with a quarter or one-fifth inch 
objective. Observe the cells of which the body walls 
are composed. Note the knotty appearance of the 
tentacles. In these projections of the tentacles and 
in the walls of the body are certain distinct oval 
cells, the thread cells. Place a drop of acetic acid 
on the slide at one edge of the coverslip, and touch 
the opposite edge of the coverslip with a piece of 
blotting paper, meanwhile watching the specimen 
closely. Examine carefully to see the thread-like 
prolongations of the thread cells which have been 
discharged as a result of the irritating acid. Small 
animals coining in contact with the tentacles are 



THE FRESH-AYATER HYDRA. 169 

paralyzed by means of these threads which are sud- 
denly shot out; the tentacles then carry the victim 
to the mouth and it is swallowed. 

Note the simplicity of the structure of hydra — the 
absence of any distinct nervous system, and all 
special organs of circulation and respiration. 

Hydras have been cut into slices, lengthwise and 
crosswise, and each part not only continued to live 
but grew into a perfect hydra. Hydras have also 
been turned inside out and in a short time digested 
food as usual, what had been the outer layer of the 
body now becoming the lining of a stomach. The 
tentacles when cut off do not live. 

Besides multiplying by budding, hydra also pro- 
duces ova and spermatozoa in projections of the body 
walls. Both kinds of sexual elements are produced 
in the same individual. Such an animal is called a 
hermaphrodite. 

There is a large group of animals, almost without 
exception marine, constructed on essentially the same 
plan as hydra, though often much more complicated. 
Hence the hydra is the type of the group known as 
the Hydroids. Many of them live in colonies, as 
if the young hydras, instead of dropping off from 
the parent and becoming distinct individuals, re- 
mained attached with a free communication between 
them all. At least two distinct forms of individuals 
are commonly found : — 

a. A hydra-like form, devoted to obtaining and pre- 
paring nourishment for the colony, hence called 
the nutritive zooid. 

b. Modified forms, producing the generative ele- 
ments, the generative zooids. 



170 PRACTICAL ZOOLOGY. 

c. Besides these two are often found forms modified 
for protection, etc. 

If a stained and mounted specimen of a campanu- 
larian or other hydroid be at hand, it will be found 
very useful in showing these points. 

The different kinds of individuals, though often 
greatly modified, still show the essential plan of the 
hydra. Some hydroids have a tube of hard material 
developed by the outer layer, and at the base of the 
colony some kinds secrete a layer of this material 
incrusting the object on which the colony is borne. 
Some forms spread by runners like strawberries. 
One form is common on the shells inhabited by her- 
mit crabs. Others are attached to seaweed, while still 
others are dredged up from great depths of the ocean. 

Among certain forms of hydroids the generative 
zooid becomes peculiarly modified in form, and ulti- 
mately becoming detached, is known as a free gener- 
ative zooid, jelly-fish, or medusa. These jelly-fishes, 
or medusae are usually either bell-shaped or umbrella- 
shaped, the part answering to the top being called the 
bell or disk. Corresponding to a short handle is the 
manubrium. This has at its free end an opening, 
the mouth. The handle is hollow, and communi- 
cates with tubes radiating through the disk, answer- 
ing to the umbrella rays. These tubes are connected 
by a circular tube, extending around the margin of 
the disk. Along this margin are tentacles and organs 
for receiving impressions of light or sound. Most 
jelly-fishes swim by contracting the umbrella-like disk. 

Along the radiating tubes, or in the manubrium, 
are borne the generative elements; the eggs develop 



THE SEA-ANEMONE. 171 

into hyclra-like forms, which, on becoming attached, 
give rise by a process of budding, to a hydroid colony, 
some members of which assume a medusa form, thus 
completing the cycle. This mode of development 
has been called, though inappropriately, an alterna- 
tion of generations. All jelly-fishes do not, however, 
develop in this way. Jelly-fishes are richly supplied 
with lasso-cells, and the larger ones sting severely, 
being dangerous to bathers. 

Read the description of Cyanea and other jelly- 
fishes in " Seaside Studies." 



THE SEA-ANEMONE. 

In its general form the sea-anemone resembles a hydra, 
having a cylindrical hollow body attached by one end to 
some foreign object, and at the free end a mouth sur- 
rounded by tentacles. In its internal structure, however, 
the sea-anemone presents some new features. The mouth, 
instead of opening directly into the body cavity, as in the 
hydra, opens into a stomach which hangs like a bag sus- 
pended in this cavity ; the stomach has no bottom, but at 
its lower end communicates freely with the body cavity. 

The body wall and stomach may be represented by a 
glove-finger with its tip cut off and the open end turned 
back part way into the larger part of the finger. 

The cavity of the body is divided into a series of radial 
compartments by fleshy vertical partitions, the mesente- 
ries, which extend inward from t lie body wall, some reach- 
ing the stomach and being attached to it, others not ex- 



172 PRACTICAL ZOOLOGY. 

tending as far inward as the stomach. Each tentacle 
communicates with one of these radial compartments, and 
is to be regarded as a mere extension of part of the body 
cavity. 

Alcoholic specimens should be sliced transversely and 
longitudinally. In a transverse section of the lower part 
of the body there will be seen the body wall with a series 
of partitions extending inward and ending in a free edge. 
The section across the upper part of the body shows an 
outer circle, the body wall, an inner circle, the stomach 
wall, and, connecting the two, the radially arranged parti- 
tions, or mesenteries. Like the hydroids, the sea-anemone 
is well provided with lasso cells. 

Food is taken into the mouth, digested in the stomach, 
then passed, mixed with sea water, into the body cavity, 
through which it is made to circulate by the contractions 
of the body walls. The indigestible portions of the food 
are expelled from the stomach through the mouth. 

The tentacles are often brilliant and variegated in color: 
and when the sea-anemone is expanded, it well proves the 
fitness of its name. For a very interesting description of 
these beautiful animals read Mrs. Agassiz's little book. " A 
First Lesson in Natural History'* (Xo. IV. in " Guides for 
Science Teaching "). 



CORAL POLYPS. 

The coral polyps are similar to the sea-anemone in their 
general structure. They usually grow in colonies with 
their bases connected by a continuous layer of living 
matter, from which the polyps grow by budding. 



COEAL POLYPS. — STONY COEALS. 173 

Through this common base the cavities of the polyps 
communicate, more or less directly, so that food obtained 
by one may nourish the whole colony. The coral polyps 
also differ from the sea-anemone in forming a deposit of 
hard matter. Representatives of the two kinds of coral 
should now be examined. 



STONY CORALS. 

{Corals Proper.^) 

In a piece of stony coral, or compound skeleton of a 
colony of coral polyps (Gralazea is a good form to study), 
make out the following points : — 

1. The nature of the material itself; test by putting a 
very small piece into weak acid, or by touching the 
specimen with a drop of acid. 

2. The cup, or theca, formed by an individual polyp, 
often traceable as a long tube. Observe, — 

a. The outer wall of the cup. 

b. The partitions, or septa, extending inward from 
the wall of the cup. 

3. Between the cups, the porous limy secretion, which 
was secreted by the common body substance, or cce- 
nosarc, connecting the individual polyps. 

Imagine the sea-anemone depositing limy matter in 
the base of its body wall, forming a cup; fleshy radial 
ridges rising from the floor and wall of the cup be- 
tween the mesenteries, and a similar deposit in these 
ridges; thus it will be seen how the cup is formed by 



174 PRACTICAL ZOOLOGY. 

the individual polyp. By the continued growth of 
the polyp, and the continuation of the limy deposit, 
the cup becomes an elongated tube. By budding are 
formed the branches of these tubes, increasing in size 
and in the number of partitions as they grow. 

4. Between the cups, a porous secretion of the same ma- 
terial as that in the cups. This is deposited in the 
common fleshy base, filling up, in some forms, the 
spaces between the cups ; and when one polyp dies, its 
cup is covered over and buried out of sight by this 
secretion of the common base. 

5. Make a drawing of a mass of stony coral, showing 
the general arrangement of the cups, their mode of 
branching, and the common secretion between them. 

6. Draw a cup as seen from its free end. Make also a 
drawing of a cross-section of the same cup toward 
the smaller end. 

In the stony corals the mesenteries are alwaj-s in 
pairs, and the fleshy ridges, in which are secreted the 
septa, arise between them. 

The tentacles are generally in multiples of six, and 
are not fringed. It is of this kind of coral that the 
reefs are formed. 



SEA-FEATHER, OR SEA-FAN. 

In a sea-feather, e.g., Muricea, note : — 

1. An outer bark-like layer; with the thumb-nail scrape 

off a little of this layer and pulverize it between the 

thumb and finger ; mix this powder with water and 

examine under a microscope. A better way to see 



SEA-FEATHER, OB SEA-FAN. 175 

the spicules is, to thoroughly clean them by boiling 
some of the outer laj^er in caustic potash. In this 
layer are holes from which the polyps protruded. In 
this form, then, the secretion is wholly in the living 
matter between the polyps, the bark-like layer being 
composed of the dried flesh in which the spicules lie 
imbedded. 

Strip off a piece of the bark-like layer and note the 
grooves on its inner surface. By examining the end 
of this piece it may be seen that these grooves are 
caused by a series of tubes running lengthwise near 
the inner surface of this layer. Find the openings of 
the tubes where they were broken ; these tubes con- 
nect the polyps of the colony. 

2. The central axis of horn-like substance. Test its flexi- 
bility and strength. Observe the grooves on its sur- 
face, and the relation between them and the tubes 
above noted. This horny axis is excreted by the 
walls of these tubes, and is not penetrated by liv- 
ing matter like the outer layer. In the precious red 
coral the central axis is formed in the same way, but 
is calcareous instead of horny, and the outer bark-like 
layer has been removed. 

3. Note the mode of branching in a sea-fan, comparing 
the margin with the central portion to see how the 
meshes are formed. Remove some of the outer layer, 
and compare with the sea-feather. In this group 
(including sea-feathers, sea-fans, the precious red coral, 
etc.) each polyp has eight fringed tentacles; also 
eight mesenteries, which are never in pairs. An alco- 
holic specimen, with the polyps expanded, should, if 
possible, be examined. 



176 PRACTICAL ZOOLOGY. 

The hydroids, jelly-fishes, sea-anemones, and coral 
polyps, with many other interesting forms, belong to 
the branch Ccelenterata. The coelenterates are many- 
celled, radially symmetrical animals, and never pos- 
sess a digestive tube wholly cut off from the body 
cavity. 



SPONGES. 

Each pupil should have a small specimen of a commer- 
cial sponge, showing large holes at the top, but not with 
large holes running straight through. 

The teacher will need several specimens of larger 
sponges ; one of the simple calcareous sponges, in alco- 
hol ; a piece of a commercial sponge in alcohol, showing 
the sponge-flesh still in place ; a silicious sponge ; and 
slides showing sponge spicules. 

The pupil should make out the following points from 
his specimen : — 

1. Its elasticity; test first the specimen dry, and again 
after wetting it. Compare the elasticity of different 
kinds of sponges. 

2. The fibrous structure ; with forceps tear off a bit of 
the sponge and examine with a lens. Then examine 
under the microscope. 

3. The sponge was attached by its basal surface to rock. 
Find where it has been trimmed away with shears ; 
perhaps if this has not been thoroughly done, some 
bits of rock may be found clinging to the base. 

4. Examine now the different channels by which the 
sponge is perforated. 



SPONGES. 177 

a. Large crater-like tubes, opening at the top of the 
sponge. Looking into these, it may be seen that 
they give off branches. If you can see right 
through the sponge by looking into these open- 
ings, you may know that too much of the base 
has been cut away* and your specimen is not a 
good one. With a razor or sharp knife, cut the 
sponge in two down one of these large tubes, and 
examine from the inside. 

b. Trace the branches of the large tubes by gently 
pushing into them a probe (a wire with a little 
knob on one end). These lead, usually, to holes 
seen on the outside. 

c. Grooves on the surface of the sponge, some shal- 
low, others already becoming enclosed by the 
union of the tufts of fibres outside of them ; in 
this way is formed another set of tubes (d). 

d. Tubes running parallel to the surface of the 
sponge, whose cut-off ends may be seen near the 
margins of the split sponge. Hold the half 
sponge up to the light to see the radiating fibres 
and the concentric series of holes indicating the 
mode of growth of the sponge. 

e. Minute branches of the above tubes penetrating 
the sponge in all directions. 

It must be borne in mind that the sponges we buy 
are only the skeletons of sponges. In the living 
sponge the skeleton is entirely imbedded in soft liv- 
ing matter, and the skeleton cannot be seen on the 
exterior ; in fact, its fibres are not very evident in a 
section of a fresh sponge. The outside of the sponges 
whose skeletons we buy, when alive resembles, in color 



178 PRACTICAL ZOOLOGY. 

and general appearance, the back of a kid glove, vary- 
ing from dark reddish-brown to almost black. The 
consistency of the living sponge is about the same as 
that of beef liver. If one of these live sponges be 
watched, a current of water is found to come out of 
the larger holes at the top, and currents pass in 
through the numerous smaller holes on the exterior. 

If the sponge be handled, many of the smaller holes 
close and entirely disappear. 

In order to understand a little more clearly the 
structure of the common sponge, and to see how the 
currents of water are maintained, an examination of a 
simple sponge will be useful. Our simplest sponges 
have no elastic skeleton composed of horn}^ fibres like 
those of the commercial sponge, but have little needle- 
shaped and three-pronged spicules of limy matter. 

One form common on the northern Atlantic coast 
is a simple or branched white tube, an inch or so in 
height and sometimes as thick as a pigeon's quill. 
These are in clusters, attached by one end and open at 
the other. Imbedded in the wall of each tube are the 
spicules above mentioned, projecting both on the out- 
side and on the inside. The inside of the tube is lined 
with cells bearing cilia which, by their vibration, drive 
the contained water out of the mouth of the tube ; to 
replace which, water enters through many holes which 
pierce the wall of the tube. In sponges a little more 
complicated, the cilia, instead of lining the main tube, 
are limited to small pouches, or lateral branches of the 
main tube, extending into the body wall and communi- 
cating with the exterior through small pores. In others 
the cilia are found only in certain enlarged portions 



SPONGES. 179 

of these radiating tubes. This represents the condi- 
tion in the commercial sponges; certain cavities are 
lined with cilia and are connected on the one hand 
with the smaller tubes entering the whole surface of 
the sponge, and on the other with the large tubes 
opening at the top. These cilia cause the currents 
above mentioned. Thus the sponge gets both food 
and oxygen. 

Sponges (including, besides those already men- 
tioned, silicious sponges, whose spicules are flinty) 
constitute the branch Porifera. 

For a very interesting account of the gathering and 
preparation of sponges for the market, read " Com- 
mercial and Other Sponges" by Hyatt (No. III. in 
" Guides for Science Teaching"). 



180 PKACTICAL ZOOLOGY. 



REVIEW OF ALL THE ANIMALS STUDIED. 

1. How many different plans of structure have been shown by the 

animals thus far examined ? 

2. How many different ways of eating, and how do the digestive 

organs differ? 

3. What different arrangements for the circulation of the blood? 

4. Compare the various methods of breathing. 

5. In what ways do animals effect motion and locomotion? 

6. Describe the different sorts of organs of feeling, seeing, hearing, 

smelling, and tasting. 

7. Describe the methods of producing sounds. 

8. What different kinds of coats do animals wear? 

9. What weapons of attack and defence do they carry? 
10. What different kinds of skeletons? 

How many kinds of animals are native to your neighborhood? 

The animals of a given region constitute its fauna. Thus, the 
faunae of North and South America are unlike; and North 
America may be divided into regions having more or less dis- 
tinct f auna3. 

What characters are common to all the animals you have studied ? 
What is an animal ? 



BRANCHES OF THE ANIMAL KINGDOM. 
(Packard.') 

8. Yertebrata : Mammals, Birds, Reptiles, Batrachians, Fishes, etc. 

7. Arthropoda: Crustaceans and Insects, Spiders, Myriapods, etc. 

6. Mollusca : Bivalves, Snails, Cuttle-fishes, etc. 

5. Vermes : Worms. 

4. Echinodermata : Crinoids, Starfishes, Sea-urchins, etc. 



BOOKS OF REFERENCE. 181 

3. Coelenterata : Hydroids, Jelly-fishes, Polyps, etc. 

2. Porifera : Sponges. 

L Protozoa : Amoeba, Paramceciura, Vorticella, etc. 



BOOKS OF REFERENCE FOR THE ZOOLOGICAL 
LABORATORY. 

Of the following books, Nos. 1 to 9 are almost indis- 
pensable. For general reference, at least, one of the first 
three should be at hand, and every one of 4 to 9 gives 
great aid in practical work. 

1. Text-Book of Zoology. Claus & Sedgyrick. Macmillan & Co. 

2 yols. 88.00. 

2. Zoology. Packard. Henry Holt & Co. §3.00. 

3. Text-Book of Zoology. Xicholson. D. Appleton &: Co. 81.50. 

4. Handbook of Inyertebrate Zoology. Brooks. Cassino. 

S3.00. 

5. Practical Biology. Huxley & Martin. Macmillan & Co. 

81.50. 

6. Practical Physiology. Foster & Langley. Macmillan & Co. 

82.00. 

7. Guides for Science Teaching. Hyatt and others. D. C. 

Heath & Co. 10-40 cts. each. 

8. First Book of Zoology. Morse. D. Appleton & Co. §1.00. 

9. Zootomy. Parker. Macmillan & Co. §2.25. 

10. The Crayfish. Huxley. D. Appleton & Co. |1.75. 

11. Anatomy of Vertebrated and Ixvertebrated Animals. 

Huxley. 2 yols. D. Appleton & Co. §2.50 each. 

12. Guide to the Study of Insects. Packard. Henry Holt & 

Co. §5.00. 

13. Insects Injurious to Vegetation. Harris. Cassino. $6.00. 



182 PB ACTIO AL ZOOLOGY. 

14. Insects Injurious to Fruits. Saunders. J. B. Lippincott 

&Co. $3.00. 

15. Vegetable Mould and Earthworms. Darwin. D. Apple- 

ton & Co. $1.50. 

16. The Naturalist's Assistant. Kingsley. Cassino. $1.50. 

17. Comparative Zoology. Orton. Harpers. $1.80. 

18. Seaside Studies in Natural History. Mrs. E. C. and 

Alexander Agassiz. Houghton, Mifflin, & Co. $3.00. 

19. Spiders, their Structure and Habits. Emerton. Cas- 

sino. $1.50. 

20. Life on the Seashore. Emerton. Cassino. $1.50. 

21. Manual of the Vertebrates. Jordan. Jansen, McClurg 

& Co. $2.50. 

22. Synopsis of the Fishes of North America. Jordan & 

Gilbert. 

23. Key to the Birds of North America. Coues. $10.00. 

24. The Butterflies of the Eastern United States. French. 

J. B. Lippincott & Co. $2.00. 

25. The Cat. Mivart. Scribners. $3.00. 

26. The American Naturalist. Cope & Packard. Monthly. 

$4.00 a year. 



TYPES OF MARINE ANIMALS. 183 

TYPES OF MARINE ANIMALS FOR LABORA- 
TORY USE. 



Protozoa. 

Foraminiferal sand. Bahamas. 

Sponges. 

Commercial sponge. Small hand specimens for class use. 

Florida Keys 25 

Same. Section mounted on slide 1 

Same. Alcoholic specimen showing fleshy matter. Small 

piece in vial 1 

Sea cap sponge. Florida Keys 1 

Calcareous sponge in vials. New England 

Microscopical prep. Showing spicules in place ..... 1 

Silicious sponge. New England 1 

Spicules of same. Mounted 1 

Chal inula. Pieces. 

Ccelenterates. 
Hydroids. 

Tubular ia. In vials. New England 12 

Tulularia. Exhibition cluster. 

Clava on seaweed; clusters in vials. New England ... 12 

Hydractinia colonies on shells 4-6 

Campanularian. In vials 12 

Campanularian colony. Stained and mounted. Slide . . 1 
Campanularian jelly-fish. Stained and mounted. New Eng- 
land 1 

Sertularia on seaweed. Dry. New England. 

ACTINOIDS. 

Sea-anemone. New England 6 

Sea-anemone. Section on slide 1 

Stony coral (Galaxea). Pacific. Small hand specimens . . 20 

Alcyonarian coral (Muricea). Dry. Florida Key-. Ex. spec. 1 

Same. Branches for class use 20 

s ne. Branch in alcohol showing polyps expanded ... 1 

Same. Slide with spicules of skeleton 1 



184 PRACTICAL ZOOLOGY. 

ACTINOIDS. 

Sea-fan. Bahamas 1 

Same. Horny axis 1 

Same. Spicules mounted 1 

Echinoderms. 

Starfish for dissection. New England 25 

Same. Dry 25 

Same. Prepared, showing skeleton 1 

Same. Decalcified 1 

Same. Injected rays showing water system 5 

Section of plate showing microscopic structure. Mounted . 1 
Young starfish showing the budding out of rays. Stained 

and mounted 1 

Large W. I. Starfish (Ore aster) 1 

Brittle stars (Ophiurans) . Dry 3 

Sea-urchins. Ale. For dissection. New England ... 25 

Same. Tests. Dry 25 

Same. Ale. specimen decalcified 1 

Same. Section of plate showing microscopic structure. Slide 1 

Large W. I. Sea-urchin (Hipponoe). Test 1 

Clypeastroid (Sand-dollar), with spines 1 

Clypeastroid (Sand-dollar), without spines 2 

Clypeastroid (Echinanthus). W. 1 1 

Holothurian. Common sea-cucumber (Pentacta). New Eng- 
land 1 

Synapta. Microscopical preparation showing plates in body 

wall 1 

Worms. 

Nereis in test-tube. Ale 1 

Polyzoan (Bugula). Dry. 

Brachiopod (Terebratulina). Ale . 2 

Mollusks. 

Clam killed with siphons extended 1 

Mussel. Ale. or shell 1 

Carnivorous sea-snail (Lunatia) 1 

Carnivorous sea-snail (Purpura) 2 

Limpet. Ale. New England 2 

Squid. New England 2 



TYPES OF MAKINE ANIMALS. 185 

Arthropods. 

Crustacea. New England. 

Lobster. Small specimen. Dry 1 

Shrimp. Ale 2 

Crab. Dry or ale 2 

Goose barnacle. Ale 3 

A corn barnacle. Dry. 

King crab (Limulus). Small specimen. Ale 2 

Same. Medium size. Dry 1 

Same. Moults. Small specimens 3 

Insects. 

White ants (Termites). In vial. Bahamas. 

Ascidians. 

Ascidia. New England 1 

Boltenia. New England 1 

Vertebrates. 

Young shark (Acanthias). 6 inches. New England ... 3 

Small skate. New England 1 

Flounder. New England 1 

The above collection, carefully prepared and designed 
especially for class work, may be obtained from B. H. 
Van Vleck, Boston Society of Natural History, Boston, 
Mass. 

Price (including packing), $25.00. 



Science. 



"Thinking again the thoughts of God.' 9 



Organic Chemistry : 



Aft Introduction to the Study of the Compounds of Carbon. By Ira 
Remsen, Professor of Chemistry, Johns Hopkins University, Baltimore. 
Adapted to the needs of all students of Chemistry, whether they intend 
to follow the pure science, or to deal with it in its application to the 
arts, medicine, etc. $% X 7%. inches, x + 364 pages. Cloth. Price by 
mail, $ 1.30 ; Introduction price, $1.20. 

THIS book is strictly an introduction to the study of the compounds 
of Carbon, or Organic Chemistry, and is intended to meet the 
wants of students in our scientific schools, medical schools, schools of 
technology, and colleges. It is difficult to see how, without some such 
general introductory study, the technical chemist and the student of 
medicine can comprehend what is usually put before them under the 
heads of "Applied Organic Chemistry" and "Medical Chemistry. 1 ' 
The book is perhaps rather more elementary than most of the existing 
small books on the subject, and is therefore, it is believed, better adapted 
to the classes of students mentioned. It takes nothing for granted 
except an elementary knowledge of General Chemistry. Special care 
has been taken in selecting for treatment such compounds as will best 
serve to make clear the fundamental principles. General relations 
as illustrated by special cases are discussed rather more fully than is 
customary in books of the same size ; and, on the other hand, the 
number of compounds taken up is smaller than usual, though all which 
are of real importance to the beginner are treated of with some degree 
of fulness. Thus there is less danger of confusion than when a larger 
number is brought to the attention of the student. The author has 
endeavored to avoid dogmatism, and to lead the student, through a 
careful study of the facts, to see for himself the reasons for adopting 
the prevalent views in regard to the structure of the compounds of 
carbon. Whenever a new formula is presented, the reasons for using 



SCIENCE. 



it are given so that it may afterward be used intelligently. Full direc- 
tions are given for making a number of typical compounds, by methods 
quite within the reach of every chemical laboratory, so that with the 
aid of the book a systematic course of laboratory work on carbon com- 
pounds may be carried on. 

The following description of the book, which is also a noteworthy 
commendation of it, we quote from a review of it by Prof. M. M. 
Pattison Muir, Cambridge University, Eng., published in Nature, 
London, June 4, 1885. 

" This is chemistry. Of how few books professing to be books on 
chemistry can it be said that they teach us anything of the science ! 
The student who begins with the study of the carbon compounds has 
to suffer many things from the text-books. Some of them present him 
with dry bones in the shape of isolated facts, and bold assertions 
regarding structural formulae and the linking of atoms. Others lead 
him into speculations which he is unprepared to follow ; he makes little 
flights into these, and comes back fancying he is a chemist. Other 
books (there are not many of them) proceed on the true scientific lines ; 
but very frequently their pages are encumbered with too many facts 
about more or less widely separated compounds, or they deal so much 
with groups of compounds, rather than with the typical individual 
bodies, that the beginner soon loses his way, becomes perplexed, and 
is ready to abandon the pursuit. 

" Prof. Remsen has shown us a more excellent way than any of these. 
He leads the learner by degrees through the early difficulties ; he places 
before him distinct and detailed accounts of a few typical compounds ; 
he shows him how these compounds are mutually related ; and then he 
takes him back to the beginning again, and teaches him how each com- 
pound he has learned to know represents a group, and how, when he 
knows the properties of one member of the group, he also knows much 
about all the members. 

" At the outset Prof. Remsen makes a few wise and pregnant remarks 
on the meaning of the structural formulae. These 'enable the chemist 
who understands the language in which they are written to see relations 
which might easily escape his attention without their aid. In order to 
imderstand them, however, the student must have a knowledge of the 
reactions upon which they are based ; and he is warned not to accept 
any chemical formula unless he can see the reasons for accepting it. 1 
The whole book is a practical sermon on this text. 



SCIENCE. 



" In no other elementary book in the English language will the student 
find so many admirably chosen examples of the formation of structural 
formulae. The important facts are noted ; then the inference is drawn ; 
then the hypothesis is ventured upon ; analogous facts are recalled ; 
the hypothesis is strengthened or weakened ; suggestions are made ; 
experiments are conducted ; and all is finally summarized in the for- 
mula. But the book is more than a selection of examples showing how 
structural formulae ought to be gained. It is a systematic although 
elementary treatise on organic chemistry. The student is first taught 
about the two paraffins, methane and ethane ; then he learns how the 
halogen derivatives of these are prepared, and what relations they bear 
to the parent hydrocarbons. By this time he has had his first taste of 
isomerism. Then he proceeds to the oxygen derivatives of methane 
and ethane ; he learns what an alcohol is ; he becomes acquainted with 
ether, aldehyde, formic, and acetic acids, some ethereal salts, and ace- 
tone. This method of studying a few simple compounds in detail is 
pursued until the student is more or less familiar with representatives 
of all the principal groups of compounds derived from the paraffins. 
He is now in a position to study these hydrocarbons as a group, and 
to deal in some detail with the questions of isomerism. When the 
paraffins and their derivatives have been thus studied, the more difficult 
subject of the benzenes and their compounds is approached. And here 
the author shows an admirable power of dealing with facts as facts, and 
with theories as theories. 

" Many admirable illustrations of the scientific method of inquiry 
are to be found throughout the book. I would especially draw atten- 
tion to the simple but thorough-going treatment of the ' equivalency 
of the hydrogen atoms ' in the molecule CH 4 (pp. 28, 29) and in the 
molecule C 6 H 6 (pp. 234-236). It is on subjects such as are discussed 
in the pages referred to that the chemical student so frequently suffers 
shipwreck. If he will use this little book by Prof. Remsen as his pilot, 
and will keep a good lookout as he proceeds, he may hope to pass the 
shoals of the hexagon-formula and the shallows of the ortho-, meta-, 
and para-derivatives of benzene. 

" The author of this book deserves the thanks of all chemical teachers 
who have tried to teach organic chemistry to beginners for the clear 
and short directions which he gives for preparing the important com- 
pounds of carbon. The book may well be used as a laboratory guide 
- no less than an introduction to the science of organic chemistry.*' 



SCIENCE. 



The Elements of Inorganic Chemistry : 

Descriptive and Qualitative. A Text-Book for Beginners, based on Ex- 
perimental and Inductive Methods. By Jas. H. Shepard, Instructor in 
Chemistry, Ypsilanti High School, Mich. 5^ by 7^ inches, xx + 377 
pages. Cloth. Price by mail, #1.25. Introduction price, $1.12. 

IT is a practical embodiment of the modern spirit of investiga- 
tion. It places the student in the position of an investigator, and 
calls into play mental faculties that are too often wholly neglected. It 
leads him to observe, to experiment , to think, to originate. Coming as 
it does from the working laboratory of a practical instructor, who has 
had the constant advice of fellow-teachers in all parts of the country, 
this text may be fairly taken as an exponent of the latest methods of 
teaching chemistry. 

Its distinctive features are: experimental and inductive methods; 
the union of descriptive and qualitative chemistry, thus allowing these 
kindred branches to supplement and illustrate each other ; a practical 
course of laboratory work, illustrating the general principles of the 
science and their application ; a fair presentation of chemical theories, 
and a conciseness which confines the work to the required limits. 

Each element and compound is treated in the following natural 
manner : — 

1. Its occurre7ice, in which the student learns where he may find it. 

2. Its preparation, or how he may obtain it for examination. 

3. Its properties and uses, 

4. Its tests, or how he may detect its presence in known or in un- 
known substances. 

Many equations are given to illustrate the chemical reactions in the 
different operations, and there are also special directions for detecting 
the acids as well as for separating the metals into groups, and isolating 
the individuals from each group. 

The work closes with full and explicit directions for successfully and 
economically equipping the laboratory, and preparing the needed re- 
agents and solutions. 

Teachers who are compelled to compress their work into a few weeks' 
course can adopt the " Briefer Course " outlined in the preface, and 
have meanwhile the benefit of a book sufficiently complete to cover any 
want likely to arise in the laboratory. But average pupils of sixteen 
years can do all the work laid down in this text. A fair class can do the 



SCIENCE. 



whole work up to the metals in twenty weeks, and all the work given 
in metals in eight or ten weeks. 

We confidently recommend Shepard's Chemistry to any teacher who 
now uses, or who wishes to adopt, the laboratory method of instruction. 

Among its many new and valuable features, a prominent teacher 
specifies the following : — 

i. Its excellent methods, which bring out the great educational force 
of the science, and yield exceptionally large practical results. 

2. The logical arrangement of its subject-matter, introducing the 
principles of the science by easy steps. 

3. Its conciseness and its completeness fully covering the beginner's 
wants in the working laboratory. 

4. Its mechanical excellence, the typography being open and attrac- 
tive, and the large type allowing the text to be read at a distance with- 
out injury to the eyes ; the binding being such that the book will stay 
open on the desk while the student is at work, and the color of the 
cloth being such as is least affected by acids. 

5. The Appendix, which gives (1) Instructions for equipping the 
laboratory ; (2) Directions for preparing all needed reagents ; (3) A 
complete list of working materials ; (4) The impurities found in com- 
mercial reagents ; (5) All the names by which reagents are known. 

The book is based upon plans and methods which have been em- 
ployed in the author's laboratory throughout a series of years, and no 
work has been incorporated in the text or in the exercises that has not 
there been proven practicable. 

A wide correspondence with the best teachers in all parts of the 
country shows that they are pursuing essentially the same plan. 
Throughout the book the aim is to make the labors of the teacher as 
light as possible, and to "place the laboratory work where it will do the 
most good in the hands of the students." 

"This work and Remsen's Organic Chemistry (page 1 of this cata- 
logue) form an admirable course for the presentation to the student 
of the facts of inorganic and organic chemistry. " — Curtis C. Howard, 
Prof, of Chemistry, Starling Med. Coll., Columbus. O. 



A Circular, suggesting various plans of shortening the course, as 
well as a Special Circular, of interest to chemists and teachers of chem- 
istry, will be sent on application to the publishers. 



26 



SCIENCE. 



The Elements of Chemical Arithmetic, 

with a Short System of Elementary Qualitative Analysis. By J. MiLNOR 
CoiT, M.A., Ph.D. y)4 by 5 inches, iv + 89 pages. Cloth. Price by 
mail, 55 cents; Introduction price, 50 cents. 

HP HIS manual is designed to supplement the teaching of ordinary 
text-books of descriptive chemistry. It is the result of the author's 
own experience in elementary science-teaching, and has been success- 
fully used by him in his own classes. The methods have therefore 
been practically tested. Part I. contains the more important rules 
and principles of chemical arithmetic, followed by a series of prob- 
lems. The matter in this part of the book is purposely very much 
condensed, and brought within the scope of the average student in 
high schools or colleges. 

Part II. contains a short system of elementary qualitative analysis. 
The simplest and best tests have been adopted, and the tables of sep- 
aration of the metals will be found to be the least complicated. Some 
tables for reference will be found at the end of the book. 

The manual will invite the examination of those who are inter- 
ested in making the teaching of chemistry more practical even to 
beginners. It is suggested that the book be used together with a good 
work in descriptive chemistry. In the preparation of this manual the 
writer has had the benefit of the advice and suggestions of several 
eminent and experienced teachers. 

Though issued so recently , the following opinions have 
come to hand:— 



A. S. Hall, Prof, of Chemistry, U.S. 
Naval Acad., Annapolis, Md. : I am very 
much pleased with the arrangement of 
the first part. It is presented in such a 
simple way as to render it well adapted 
to schools in which elementary sciences 
are taught. (May 22, 1886.) 

T. H. Norton, Prof, of Chemistry, 
Univ. of Cincinnati, O : It is admirably 
written, and I regard it as well adapted 
to supplement the ordinary descriptive 
text-book or series of lectures, especially 
for high-school training preparatory to 
scientific courses. ■ {May 12, 1886.) 



W. K. Higley, Prof of Chemistry, 
Univ. of Chicago : I like it very much. 
We shall use it next year in our labora- 
tory, and I have recommended it to this 
year's students. (June 5, 1886.) 

John W. Fox, Prof, of Chemistry, 
Georgetown Coll., D.C.: It is an excellent 
little book. (May 15, 1886.) 

J. W. Holland, Prof, of Chemistry, 
yefferson Medical Coll., Philadelphia, 
Pa.: It is an excellent manual, and will 
be of great service to teacher and pupil, 
(June 5, 1886.) 



SCIEXCE. 25 



The Laboratory Note-Book. 

For Students using any Chemistry. 4^ by 7% inches. Board covers. 
Cloth back. 192 pp. Price by mail, 40 cts.; Introduction price, 35 cts. 

IT contains blanks for experiments ; blank tables for the reactions of 
the different metallic salts : pages for miscellaneous matter ; and an 
extra chart for the natural classification of the elements similar to that 
on page 221 of Shepard's Chemistry. This may be rolled into a 
cylinder by the student. 

The advantages of using this note-book are, briefly, these: It saves 
time for the student ; its size is convenient : and it is cheaper than an 
ordinary blank-book. The paper is such that it readily takes ink with- 
out blotting or smearing, and it may be used with a lead pencil. 

The value of systematic note-taking by the student in chemistry can 
hardly be over-estimated. The careful analyst habitually keeps record 
of his work, and thus the greater portion of our most valuable chemical 
literature has originated. If the expert finds his notes to be of ines- 
timable value to him. what shall we say in the case of the beginner? 
Evidently, that he should form, at the very outset, those habits which 
will tend to make him accurate, and which will insure his after-success. 

In the note-book the teacher has a most potent ally ; for, through its 
aid, he may know just how his students are doing their work, and can 
therefore better adapt his teaching to their needs. 

Our Special Circular contains fac-similes of three pages, prepared 
by the students in the Ypsilanti high school for 1885-6, showing how 
the book is to be used. 

Robt. B. Warder. Prof, of Chemistry, I plan very well for the purpose intended. 



Purdue Univ., Lafayette, hid. : It strikes 
me very favorably. I think further ex- 
amination may lead me to introduce it in 
Purdue University next fall. (Apr. 24, '86.) 

P. J. Roche, Prof, of Chemistry, Uni- 
versity Coll., Toronto, Out. : I have been 
struck with the excellence of the second 



(April 24, 1886.) 

A. Wanner, Prin. of York High 
School, Pa.: Laboratory Notes in the 
hands of students will encourage system- 
atic experiment. It is a good book for 
beginners, who have not the experience 



part as a means of tabulating results of - vet to enable them to Judiciously use a 
simple qualitative analysis, -something blank-book. It not only will lead to tre- 
most students sadlvneed. (May 15, i3S6.) ^ uent reference to the chemistry used, but 

will cultivate a habit of accurately, c. ■ 
Chas. W. Hargitt, Prof of Natural and briefly recording known conditions. 
Science, Moore's Hill Coll., Ind.: I like the (March 1, 1886.) 



28 SCIENCE. 

First Book in Geology. 

By N. S. Shaler, Professor of Paleontology, Harvard University. $% by 
*] x / 2 inches. Cloth, xvii+255 pages, with 130 figures in the text. 74 pages 
additional in Teacher's Edition. Price by mail, $1.10; Introduction, $1.00. 

npHE design of this book is to give the student from ten to fifteen 
years of age a few, clear, well-selected facts that may serve as a 
key to the knowledge of the earth. The number of facts dealt with 
is far less than is usually given in such books, but pains is taken in 
their presentations to make them open the way to the broadest veins 
that the science affords. The aim is to illustrate the principles of 
geology by reference to as many facts of familiar experience as pos- 
sible. 

The first part of the book treats of the simpler phenomena of a 
physical sort, the movements of the water and the air, and their effect 
on the machinery of the earth's surface ; then the simpler underground 
actions are taken up, such as the formation of veins, the folding of 
mountains, and the forces that lead to earthquakes and volcanoes. 
The latter half of the book is given to the history, in outline, of the 
earth's organic life. This is treated in a very general way, in order to 
show the student only the great steps of advance, and the method in 
which they are accomplished. 

In the appendix is a brief account of certain more important mineral 
species, arranged to give the student an outline of mineralogy, and 
some idea of the common uses of minerals. 

The Teacher's Edition contains seventy-four pages of directions for 
those who use the book in class instruction. First there are general 
directions for the guidance of teachers in their work in natural history, 
then each chapter of the book is taken up in turn, and the instructor is 
told how to supplement each lesson, by reference to facts that may be 
easily accessible in the nature about the school. 

The instructor who will make proper use of these pages will always 
find it possible to enliven the printed page with many an illustration of 
value to his students. And the average reader who desires to get a 
glance at geology and a general notion of its bearings on ordinary life, 
will find this edition of exceeding interest. It is being used in many 
schools as a Supplementary Reader, and is admirably adapted for such 
purpose. 



SCIENCE. 35 



Illustrations of Geology and Geography. 

For Use in Schools and Families. By N. S. Shaler, Professor of Palaeon- 
tology, assisted by Wm. M. Davis, Assistant Professor of Physical Geography, 
and T. W. Harris, Assistant in Botany, m Harvard University. 

CONSISTING of twenty large photographs and an equal number of 
colored plaster models. The photographs are separately mounted 
on suitable light frames, 15x20 inches in size. They represent a wide 
range of terrestrial phenomena, seashores, valleys, glaciers, mountains, 
volcanoes, caverns, etc. Alongside of each photograph is a detailed 
description of the important points illustrated in the picture, with 
occasional small diagrams, designed to show the detailed structure of 
the field ; also references to the features in the models, which serve to 
explain the facts shown in the view. 

The models, which are colored, are each 7x5 inches, and about 
2 inches thick. One series shows the principal features of horizontal, 
tilted, and folded stratified rocks, and the varied effects of river and 
ocean erosion upon them ; others exhibit the process of development 
of a volcano, of coral islands, of ocean shores, glaciers, etc. These 
models are separately mounted on wooden backs, to which are appended 
descriptions of the structures indicated, with reference to the photo- 
graphs. 

In the text appended to both models and photographs, there are 
abundant references to several text-books, where further information 
may be obtained. They are large enough to be seen, when in the in- 
structor's hand, by a class of thirty students. They are designed to 
hang on the wall, and may, when necessary, be passed from hand to 
hand without injury. 

The price of the full collection of fifty pieces, securely boxed for 
transportation, is one hundred dollars. A smaller set, containing ten 
models and ten photographs, will be sold at fifty dollars. When desired, 
the collection will be divided, and the models or photographs sold sep- 
arately ; the price for each set of twenty-five pieces will be fifty dollars. 
Specimen copies of the models and photographs, one of each, to show 
the nature of the method, will be sent by express, carriage paid, on 
receipt of four dollars, which will be returned tm the receipt of the 
objects in good order, or accounted for if the collection is taken. A 
circular containing a detailed list of the models and photographs will be 
sent on application. [Ready slug. I. 



36 SCIE5TCE. 

Guides for Science Teaching. 

Published under the auspices of the Boston Society of Natural 
History. 

INTENDED for the use of teachers who desire to practically instruct 
their classes in Natural History, and designed to supply such infor- 
mation as they need in teaching and are not likely to get from any 
other source. 

These Guides were prepared solely as aids to teachers, — not as text- 
books. The plan of teaching followed throughout is based upon the 
assumption that, — 

Seeing is the first step on the 7'oad to knowledge ; that, — 

How much the child learns in his early years is of little importance, 
— how he learns, everything; that, — 

The teacher's work is not to teach the facts, but to lead the mind of 
each pupil to work out for itself the simple physical proble?ns witnessed 
or described, and to cultivate the habit of observatioji and of persever- 
ance in investigation. 

The Series at present consist of the following numbers : — 

About Pebbles, (No. I.) 

By Alpheus Hyatt, Professor of Zoology and Paleontology in the Massa- 
chusetts Institute of Technology. 4^ by 6 inches. Paper. 26 pages. 
Introduction price, 10 cents. 

This pamphlet is an illustration of the way in which a few common 
objects may be used to cultivate the powers of observation, and to 
teach interesting lessons in elementary natural science. It contains all 
the suggestions necessary to enable any teacher to make the lesson, or 
lessons, a complete success. 

Concerning a Few Common Plants. (No. II.) 

By George Lincoln Goodale, Professor of Botany in Harvard Univer- 
sity. 4^ by 6 inches. Paper. 61 pages. Introduction price, 10 cents. 

The design of these lessons is to point out one method by which a 
few of the more important and easily observed facts can be taught 
respecting the structure, growth, and work of plants. The purpose 
of this Guide is to call attention to the manner of preparing the 



SCIENCE. 37 



objects selected for such elementary study, and to furnish suggestions 
as to the way they can most readily be turned to good account. The 
appliances recommended are of the most trifling cost. Even simple 
lenses are not absolutely required for any of the studies suggested. 

Commercial and Other Sponges. {No. III.) 

By Professor Alpheus Hyatt. Illustrated by 7 plates. 4% by 6 inches. 
Paper. 43 pages. Introduction price, 20 cents. 

This little manual gives an account of the sponges in common use, 
and amply illustrates their processes of growth, and the methods of 
obtaining them and preparing them for the trade. The skeletons are 
present to the eye every day, and even the dullest scholar will under- 
take with interest to find out their different qualities, their common 
names, where they come from, and how they are formed. 

A Set of Eight Specimens has been prepared for the use of 
classes taking these lessons, and will be furnished for $1.00. 

A First Lesson in Natural History. {No. IV.) 

By Mrs. Elizabeth Agassiz. Illustrated by woodcuts and 4 plates. 4^ 
by 6 inches. Paper. 64 pages. Introduction price, 25 cents. 

A general history of hydroids, corals, and echinoderms, written in 
narrative form, for very young children, under the direction of Prof. 
Louis Agassiz. Amply illustrated. 

While scientifically accurate and clear, it is as simple and fascinat- 
ing as a wonder story. No fairies could more completely win the 
interest of children than do sea-anemones, corals, jelly-fishes, star- 
fishes, and sea-urchins, as described and represented in this little 
book. 

A Set of Twenty-four Specimens, to accompany Guides IV. and 
V., will be furnished for $2.00. 

Common Hydroids, Corals, and Echinoderms. {No. r.) 

By ALPHEUS HYATT. Amply illustrated. 4%hf 6 inches. Paper. 32 
pages. Introduction price, 20 cents. 

This pamphlet shows how the studies, or observations, arc to be 
most satisfactorily made, and supplies such information as one ne</ S 



38 SCIENCE. 



in teaching, and is not likely to get from any other source. The illus- 
trations are remarkably clear and suggestive ; but, to teach the pupil 
the value of personal observation and a correct habit of study, nothing 
can take the place of specimens. It is desirable that those who are to 
use this Guide shall be able to refer to No. IV. of this series, which is 
frequently quoted. 

A Set of Twenty-four Specimens, to accompany Guides IV. 
and V., will be furnished for $2.00. 

Mollnsca. Oyster, Clam, and Other Common Mol- 

lusks. (No. VI) By Aitheus HYATT. Illustrated with 17 plates, con- 
taining jj figures. 4J4 by 6 inches. Paper. 65 pages. Introduction 
price, 25 cents. 

This book not only holds in compact form all that need be taught 
beginners about the oyster, clam, and other common mollusks, but is 
invaluable as illustrating in detail the natural method of teaching. 
From first to last, the pupil is a discoverer ; the teacher is simply the 
guide, — the pupil is self-taught. The author condescends to the 
simplest things, and tells in the plainest way just how to lead the class 
to make, in proper order, the necessary investigations and discoveries. 
The most inexperienced teacher will be able, with this manual, to give 
these lessons with success. 

A Set of Seventeen Specimens to be used in giving the lessons 
outlined in Guide No. VI. will be furnished for $1.00. 

Worms and Crustacea. (No. VII.) 

By Alpheus Hyatt. Illustrated. 4% by 6 inches. Paper. 68 pages. 
Introduction price, 25 cents. 

The space given to the description of the lobster (and fresh-water 
crayfish) will, it is hoped, incite teachers to occupy more time in dealing 
with some one common animal, and thus cultivating the habit of close 
observation. The specimens needed for the lessons upon worms are 
the common earthworms and the Neresis. In these lessons, as in the 
preceding, the children are to be discoverers, not mere learners, — they 
are to be taught by experience the value and the pleasure of direct per- 
sonal observation. 



SCIENCE. V) 



A Set of Fifteen Specimens, to be used in connection with 
Guide VII., will be furnished for $1.00. 

Orders for Specimens to accompany Guides ///., IV., V., VI , or 
VII., should be addressed to Samuel Henshaw, Boston Society of 
Natural History, Boston, Mass. 

Larger collections, and sets for students' use, containing ten, twenty, 
forty, and sixty specimens of a single form, can be obtained by special 
arrangement with Mr. Henshaw. 

Common Minerals and Rocks. {No. XII.) 

By W. O. Crosby, Assistant Professor of Mineralogy and Lithology in the 
Massachusetts Institute of Technology. Illustrated. 4^ by 6 inches. 
Paper. 200 pages. Introduction price, 40 cents. Cloth, 60 cents. 

This includes, first, a brief and simple account of the principal geo- 
logical agencies ; second, descriptions of about twenty minerals of which 
rocks are chiefly composed, and of all the more common and important 
varieties of rocks ; and, third, an explanation of the leading kinds of 
structure occurring in rocks, such as stratification, folds, faults, joints, 
etc. This last section of the Guide is illustrated by forty figures, which 
add very materially to the clearness and value of the text. 

Especial prominence is given to the easy identification of the com- 
mon minerals and rocks, and to the constant association, in the mind, 
of the rocks and rock-structures with the agencies by which they have 
been formed. 

This little volume is not merely a guide to teachers, but it is also a 
simple and logical presentation of the leading facts and principles of 
structural geology, and is well adapted for class use. It is hoped, how- 
ever, that teachers will base their instruction upon specimens of min- 
erals and rocks, using this work more as a reference book than as a 
text-book, in the hands of pupils. Natural science cannot be success- 
fully taught with books alone ; and even the best books should sup- 
plement, but not precede or take the place of, actual observation. 

Specimens to illustrate Guide No. XII, comprising the twenty 
principal elements and minerals, are supplied in durable, covered boxes, 
properly labelled, as follows : — 

I large specimen of each kind, 20 in all, labelled . . . $ .50 

5 smaller specimens of each kind, 100 " M ... 1.25 

10 " " " " 200 " " ... 225 

20 " " " " 400 " " ... 400 



40 SCIENCE. 

Ten additional varieties are supplied in the same way : — 

I large specimen of each kind, 10 in all, labelled . . . $ .30 

5 smaller specimens of each kind, 50 M " ... .75 

10 " " " " 100 " f * ... 1.50 

20 " " " " 200 " '* ... 2.50 

Orders for these specimens should be addressed to Prof. W. o 
Crosby, Boston Society of Natural History, Boston, Mass. 

First Lessons in Minerals. {No. XIII.) 

By Ellen H. Richards, Instructor in Mineralogy, Massachusetts Insti- 
tute of Technology. 4^ by 6 inches. Paper. 50 pages. Introduction 
price, 10 cents. A valuable introduction to Guide No. XII. 

The outline of the lessons was first worked out with three successive 
classes of children, from six to eight years old, just out of the Kinder- 
garten. The lessons were then given to classes in two public schools 
in the city of Boston. During the two years which have since elapsed, 
they have been given to about one thousand children of the fourth 
classes of several of the Boston Grammar Schools. They have also 
been adopted by teachers in other places. Such changes have been 
made as experience has shown to be desirable, and the Guide is now 
presented in a form which can be recommended to teachers in general. 
The specimens to illustrate Guide No. XIII. consist of large, 
carefully selected cabinet specimens, with printed labels. It is desirable, 
however, to have a specimen of each type for every pupil, or at least 
for every two or three pupils. To meet this need, duplicate collections 
of somewhat smaller specimens, numbered but not labelled, have been 
prepared. 





50 specs. 


80 specs. 


125 specs. 


150 specs. 


Cabinet size, 


£2.00 


$4.00 


$8.00 


$10.00 


Student size, 2-5 colls. 


1. 00 ea. 


2.00 ea. 


4.00 ea. 


5.00 ea. 


« 6-10 " 


.90 ea. 


1.80 ea. 


3.60 ea. 


4.50 ea. 



The student collections are not sold singly. 

Other collections, adapted to more extended courses, are supplied as 
follows : — 

Minerals. 50 specs. 100 specs. 150 specs. 

Cabinet size, $6.00 $15.00 $3000 

Student size, 200 5.00 10.00 



44 



SCIENCE. 



Elementary Course in Practical Zoology. 

By B. P. Colton, A.M., Teacher of Science, Ottawa High School, 111. 
SA by 7/^ inches. Cloth, xiv +182 pages. Price, by mail, 85 cts. Intro- 
duction price, 80 cts. 

THIS work is designed to aid the student in getting a clear idea 
of the animal kingdom as a whole, by the careful study of a few 
typical animals. 

The student is first told how to collect and preserve the material for 
his study. He is then given detailed directions for its examination 
and dissection. It is not described for him, thus robbing him of the 
opportunity to develop his own powers of description, but its parts are 
named, giving barely enough of description that he may be sure to 
recognize and apply the proper name to each. He is thus led to 
observe and describe for himself. His attention is especially called 
to some of the less obvious points, but explanations are seldom given 
except when lack of time or ability renders it unlikely that he will prove 
able to solve the problem unaided. 

All the animal sub-kingdoms are represented, more attention being 
paid to those forms which the student is likely to find. He is led to 
compare them, one with another, and by noting their resemblances and 
differences he is shown how to classify animals, rather than taught a 
system of classification. 

The work is limited to what can be done by the average high-school 
pupil, as proved by the experience of several years during which these 
guides to the study of animals have been in use. 

The following opinions are from those who have read 
the tvorJc in manuscript or proof : — 



Alpheus Hyatt, Boston Society of 
Natural History: The book is a very 
fine thing. The author knows his sub- 
ject. (Dec. 11, 1885.) 

David S. Jordan, Pres. Indiana 
Univ. (author of "Synopsis of Fishes of 
N. A.") : I have looked over the book 
with much interest. It strikes me as 
just the thing for teaching general zool- 
ogy in high schools. I have long since 



given up zoological text-books as a bad 
job, believing that no book which could 
be used vjithout specimens had any value 
to the student. This is just the book we 
need for beginning zoological work in a 
scientific spirit. I can promise you that 
we shall adopt it here for beginning 
classes, and think I shall not be dis- 
appointed in it. It will be a great help 
to me, as to many other teachers of 
science. 



SCIENi 



45 



W. K. Brooks, Director of the Ches- 
apeake Zoological Laboratory, Johns Hop- 
kins Univ. : I have examined the Ms. of 
your proposed book on zoology, for use 
in schools, and I am glad that the author 
has undertaken to make his experience 
in teaching natural science available for 
other teachers, who have not had the 
special training in this branch of science 
which he has enjoyed. I am sure that 
the book will meet with a ready sale, 
and will be very useful to teachers. 
{Dec, 1885.) 

S. A. Forbes, Prof, of Zoology, Univ. 
of Illinois, and State E?ito?nologist : It 
seems to be in every way skilfully pre- 
pared, and cannot but be both useful and 
successful. This is just such a piece of 
work as has long been needed in public 
schools. 

Newton Bateman, President Knox 
Coll., Galesburg, III. (formerly Supt. of 
Public Instr. of the State of III.) : If you 
are able to develop the whole subject 
with the clearness and charm of these 
specimen chapters, the result will be a 
very useful and fascinating book. It will 
train the faculties of observation to alert- 
ness and accuracy. It will bring that 
deep satisfaction which comes only from 
original work; from getting first-hand 
knowledge. It will vitalize the half-dead 
facts of mere book and memory by the 
quickening and realistic power of the eye 
and the hand, directed by keen curiosity 
and the wide-awake mind. The book is 
needed. It will be welcomed and ap- 
preciated. 

Henry Raab, State Supt. of Public 
Instruc, Springfield, III. : This is a work 
that presents, for the first time, a guide 
for the teacher, by means of which he may 
introduce the pupils to the science suc- 
cessfully, i.e., that they may like the study 
of nature, may prepare for more advanced 
science work, and gain a lasting benefit 
for their intellectual development. I shall 
commend it to teachers of science in our 



public schools whenever I have an op- 
portunity. 

L. M. Underwood, bistructor in 
Zoology, Syracuse Univ., N.Y. : I am 
more and more pleased with it as it pro- 
ceeds. I expect to make use of the book 
in my classes next fall. (June 26, 1886.) 

M. L. Seymour, Prof of Zoology, 
III. Normal Univ. : I have no criticisms. 
I find the plan, directions, description, 
and wording excellent. I want to use the 
book in my classes as soon as published. 

J. H. Pillsbury, Biological Labor- 
atory, Smith Coll., A 7 orthampton, Mass. : 
The plan seems to me to be a very good 
one for the work for which the author 
has intended it. I am glad to see so 
good a plan offered for our high schools. 
If the remainder of the work is equally 
good, it ought to be a success. 
(March 19, 1886.) 

E. P. Jackson, Teacher of Zoology, 
Boston Latin School : I think the pages 
I have examined excellent. All enlight- 
ened teachers are aiming at the very 
standard in general which these pages 
reach in particular. If I had a book in 
my class constructed on precisely this 
model, I should use it with great confi- 
dence and zeal. (Nov. 10, 1885.) 

O. S. WestCOtt, Prin. N. Div. High 
School, Chicago, III. : The book is at- 
tractive. I think it would sell with 
thoughtful teachers. 

J. Y. Bergen, Jr., Prin. of High 

School, Peabody, Mass. : I have gone over 
the manuscript with care, and feel satis- 
fied that there is no American book on 
zoology adapted for use with high-school 
classes which will enable them to learn 
so much at first hand as they can from 
this book. It does for the pupil what 
without it the conscientious teacher must 
otherwise do for him by constant and 
laborious reference to the fuller works. 
(Jan. 3, 1886.) 



46 SCIENCE. 



How to Find the Stars. 



T i 



By Rev. James Freeman Clarke. 4% by 5^ inches. Paper. 47 pages. 
Introduction price, 15 cents. 

'HE object of this little book is to help the beginner to become 
better acquainted, in the easiest way, with the visible starry 
heavens ; to know the winter and summer constellations, and the 
principal fixed stars. It shows the position of the constellations at 
different periods of the year, giving their place in each of the four 
seasons. It also shows how to find the separate clusters by a series of 
triangles and diagrams, covering the whole heavens, and connecting 
each constellation with its neighbors. It indicates the most interesting 
objects at each period of the year, especially such as can be found with 
a telescope of moderate power. It closes with a description of the 
Astronomical Lantern. 

An Astronomical Lantern. 

Invented by Rev. James Freeman Clarke, Boston. Japanned tin; the 
face (6^ by 10 inches in size) is of ground glass, behind which lights may 
be placed. Thirty-two constellations are photographed upon seventeen 
slides of semi-transparent card-board, and stars of four magnitudes are rep- 
resented by perforations of proper size. The maps have been prepared 
under Dr. Clarke's personal supervision, and the plates, being photographed 
from the original drawings, are correct in every particular. The former price 
of the Lantern was $6.00 ; we now offer it, in improved form, with the 
slides, and a copy of " How to Find the Stars," for $4.50. The whole care- 
fully packed in a wooden box, with sliding cover. 

n^HE object of this useful piece of apparatus is to facilitate the 
study of stellar astronomy. It is intended for beginners in 
astronomy in schools and in families, and, in fact, for all who desire 
to become acquainted with the constellations. 

The difficulty hitherto experienced in this study, and which is obvi- 
ated by the use of the lantern, is this : In order to study the starry 
heavens, it has been necessary to use an astronomical atlas or a celes- 
tial globe. These must be examined in the house, by the light of a 
lamp. The observer, having found his constellation on the atlas, goes 
out to look for it in the sky. But by the time he gets out of doors, 
he has forgotten how it looked on the atlas. And when he has found 
it in the sky, he forgets how it looked there, before he gets back to his 
atlas or globe. 



SCIENCE. 



47 




Now, the astronomical lantern makes the study of the stars perfectly 
simple and easy. It is constructed like a dark-lantern, closed on three 
sides, and on the fourth provided with a ground glass, in front of 
which maps can be inserted. On each of these maps, which are semi- 
transparent, is represented a constellation, the places of the stars 
being indicated by perforations, through which the light shines. The 
largest perforations are for the stars of the first magnitude, and the 
smaller, in due proportion, for the lesser stars. The student, there- 
fore, wishing to observe any particular constellation or cluster, has 
only to light a candle within the lantern, insert the appropriate slide, 
and go out into the night. Holding up the lantern in one hand, he 
can compare the constellation as it appears on the lantern with that in 
the sky, until he becomes perfectly familiar with the latter. 

It is easy to see how much the use of such a lantern facilitates the 
whole stud)\ In fact, we think that henceforth no one wishing to 
become acquainted with the heavens can afford to dispense with it. 
The increased ease of the study should also enlarge the number of 
students in this interesting department of science. 

The folloiving testimonials as to its value have been 
recently received : — 



C. A. Young", Prof, of Astronomy, 
Priticeton Coll. : I find it to be an admir- 
ably contrived apparatus for its purpose, 
— simple, easily managed, and effective. 
I think an adequate knowledge of the 



constellations could be obtained by its 
use, in connection with the little book that 
accompanies it, more rapidly and easily 
than from the most elaborate and expen- 
sive celestial globe. (Aug, 8, 1885.) 



Science. 



An Introduction to the Study of the Compounds of Carbon. By Ira Remsen, Pro- 
fessor of Chemistry, Johns Hopkins University, Baltimore, x + 364 pages. Cloth. Price by 
mail, $1.30; Introduction price, $1.20. 



Organic Chemistry: 

An Introduction to the Study 
fessor of Chemistry, Johns Hopkins 
mail, $1.30; Introduction price, $1.2 

The Elements of Inorganic Chemistry: 

Descriptive and Qualitative. By James H. Shepard, Instructor in Chemistry in the 
Ypsilanti High School, Michigan, xxii + 377 pages. Cloth. Price by mail, $1.25; Introduc- 
tion price, $1.12. 

The Elements of Chemical Arithmetic : 

With a Short System of Elementary Qualitative Analysis. By J. Milnor Coit, 
M.A., Ph.D., Instructor in Chemistry, St. Paul's School, Concord, N.H. iv + 89 pages. 
Cloth. Price by mail, 55 cts.; Introduction price, 50 cts. 

The Laboratory Note-Book. 

For Students 7tsiug any Chemistry. Giving printed forms for "taking notes" and 
working out formulae. Board covers. Cloth back. 192 pages. Price by mail, 40 cts. ; Intro- 
duction price, 35 cts. 

Elementary Course in Practical Zoology. 

By B. P. Colton, A.M., Instructor in Biology, Ottawa High School. 

First Book of Geology. 

By N. S. Shaler, Professor of Palaeontology, Harvard University. 272 pages, with 130 
figures in the text. 74 pages additional in Teachers' Edition. Price by mail, $1.10; Intro- 
duction price, $1.00. 

Guides for Science -Teaching. 

Published under the auspices of the Boston Society of Natural History. For 
teachers who desire to practically instruct classes in Natural History, and designed to supply 
such information as they are not likely to get from any other source. 26 to 200 pages each. Paper. 

I. Hyatt's About Pebbles, 10 cts. 
II. Goodale's Few Common Plants, 15 cts. 

III. Hyatt's Commercial and Other 

Sponges, 20 cts. 

IV. Agassiz's First Lesson in Natural 



VI. Hyatt's Mollusca, 25 cts. 
VII. Hyatt's Worms and Crustacea, 



25 cts. 

XII. Crosby's Common Minerals and 
Rocks, 40 cts. Cloth, 60 cts. 

XIII. Richards' First Lessons in Min- 
erals, 10 cts. 



History, 20 cts 
V. Hyatt's Corals and Echinoderms, 
20 cts. 

The Astrono7nical Lantern. 

By Rev. James Freeman Clarke. Intended to familiarize students with the constella- 
tions by comparing them with fac-similes on the. lantern face. Price of the Lantern, in im- 
proved form, with seventeen slides and a copy of " How to Find the Stars," $4.50. 

How to Find the Stars. 

By Rev. James Freeman Clarke. Designed to aid the beginner in becoming better 
acquainted, in the easiest way, with the visible starry heavens. 



D. C. HEATH & CO., Publishers, 
3 Tremont Place, Huston. 



INDEX. 



Abdomen 

of clam, 50. 

of crayfish, 24. 

of cricket, 9. 

of frog, 88. 

of grasshopper, 5. 

of rabbit, 121. 

of sow-bug, 36. 
Air-bladder, 85. 
Air-sacs, 6, 110. 
Amoeba, 62. 
Analogy, 85. 
Antenna, 1, 10, 29. 
Arachnida, 22, 40. 
Arteries 

of clam, 52. 

of crayfish, 32. 

of fish, 79. 

of frog, 90. 

of pigeon, 112. 

of rabbit, 123, 132. 

of sheep, 138, 142. 

of snake, 100, 101. 
Arthropoda, 40. 
Assimilation, 65. 
Batracliia, 97. 
Beetle, 17. 
Bell animalcule, 60. 
Bladder 

of fish, 78. 

of frog, 89. 

of rabbit, 122. 
Blood, 

circulation of, 91. 

of earthworm, 41. 

of frog, 92. 
Books of reference, 181. 
Brain 

of fish, 82. 

of frog, 92. 

of pigeon, 115. 

of rabbit, 126, 129. 
Breeding cages, xv. 
Bumble-bee, 10. 
Butterfly, 11. 
Cabbage worm, 13. 
Caeca 

of fish, 77. 

of grasshopper, 7. 

of pigeon, 111. 

of rabbit, 122. 

of starfish, 154. 
Capillaries, 91. 
Carapace 

of crayfish, 24. 

of turtle, 102. 
Cartilage, 135. 
Cephalo thorax 

of crayfish, 24. 

of spider, 21. 
Cilia, 50, 59. 
Clam, 46. 



Classification, 12, 20, 40, 180. 
Ccelenterata, 176. 
Coleoptera, 19. 
Collecting insects, xii. 
Coral polyps, 172. 
Crayfish, 24. 
Cricket, 9. 

Crustacea, 35, 37, 38. 40. 
Cyclops, 37. 
Development, 119. 

of butterfly, 13. 

of chick, 118. 

of clam, 55. 

of crayfish, 35. 

of dragon-fly, 19. 

of fly,l6. 

of frog, 96. 

of grasshopper, 8. 

of sea-urchin, 164. 
Diaphragm, 124. 
Differentiation, 66. 
Digestion, 65. 
Digestive organs 

of clam, 53. 

of coral polyps, 173. 

of crayfish, 33. 

of earthworm, 41. 

of fish, 76. 

of frog, 89. 

of grasshopper, 7. 

of hydra, 167. 

of pigeon, 111. 

of rabbit, 121. 

of sea-urchin, 163. 

of snake, 100. 

of starfish, 154. 

of turtle, 103. 
Diptera, 16. 
Dissecting pan, 31. 
Dragon-fly, 19. 
Ear 

of crayfish, 29. 

of tish, 84. 

of pigeon, 105. 
Earthworm, 40. 
Echinodermata, 164. 
Egg 

of butterfly, 13. 

of crayfish, 35. 

of cyclops, 38. 

of fish, 78. 

of fly, 16. 

of frog, 89. 

of grasshopper, 6, 8. 

of hen, 116. 

of mammal, 118. 

of sea-urchin, 165. 

of sow-bug, 37. 
Embryology, 119. 
Esophagus. See Gullet. 
Eustachian tube, 88, 134. 
Eye of beetle, 17. 



Eye of fish, 73, 83. 

of grasshopper, 1. 

of ox, 145. 

of snail, 57. 
Excretions, 65. 
Fisb, 70. 
Feathers, 107. 
Fly, 15. 
Frog, 86. 
Function, 45. 
Ganjrlia 

of clam, 55. 

of crayfish, 34. 

of earthworm. 43. 

of grasshopper, 8. 

of rabbit, 128. 
Gill 

of clam, 50. 

of crayfish, 26. 

of fish, 74. 
Gland, salivary, 

of rabbit, 133. 
Glottis 

of frog, 88. 

of snake, 100. 
Grasshopper, 1. 
Gullet 

of crayfish, 33. 

of earthworm, 42. 

of fish. 77. 

of rabbit, 122. 

of sheep, 136. 

of snake, 100. 
Heart 

of clam, 51. 

of cravflsh, 32. 

of fish, 79. 

of grasshopper, 6. 

of pigeon, 112. 

of rabbit, 132. 

of sheep, 136, 139, 142. 

of snake, 100. 

of turtle, 103. 
Hemiptera, 17. 
Hermaphrodite, 44, 169. 
Homolosv, 85. 
Hydra, 166. 
Hymenoptera, 11. 
Insecta, 20, 40. 
Intestine 

of crayfish, 34. 

of earthworm, 41. 

of fish, 77. 

of grasshopper, 7. 

of rabbit, 121. 

of snake, 101. 
Jellyfish, 170, 171. 
Kidney 

of clam, 52. 

of fish, 78. 

of frog, 90. 

of pigeon, 113. 



INDEX. 



Kidney 

of sheep, 125. 

of snake, 101. 
Labor, physiological divis- 
ion of, 69. 
Lacteals, 125. 
Larynx, 117. 
Lepidoptera, 12. 
Ligament, 135. 
Liver 

of clam, 53. 

of crayfish, 33. 

of fish, 76. 

of pigeon, 111. 

of rabbit, 122. 

of snake, 101. 

of turtle, 103. 
Lung 

of frog, £0. 

of pigeon, 112. 

of sheep, 136. 

of snake. 100. 

of spider, 22. 

of turtle, 103. 
Madreporic bodv, 153,161. 
Mantle, 48. 
Medusa, 170. 
Mesentery 

of fish, '77. 

of frog, 89. 

of pigeon, 111. 

of rabbit, 122. 

of starfish, 154. 
Mollus. 

Mounting insects, xiv. 
Muscle, 

action of, 95. 

insertion of, 94, 114. 

origin of, 94, 114. 

Bbeath of, 94, 114. 

structure of, 94, 136. 

of clam. 5i >. 

of crayfish, 33. 

of earthworm, 4:;. 

of eyeball, 83, 144. 

of fish, si. 

of frog, 94. 

of grasshopper, 7. 

of rabbit, 121. 
Myriapoda, 23. 
Nerves 

of clam. 55. 

of era] fish, .'14. 

of earth* orm, 48. 

offish, 77, 

of froj 

of pigeon, 110. 

of rabbit, L30. 
Irtish, 154. 
ptera, 20. 
Nutrition, I 
Organ, 15, 

iptera, 10. 
Ovary 

m\ ti-h, :;::. 

Of fish, 77. 

of froi 



Ovary 

of pigeon, 113. 

of snake, 101. 

of turtle, 103. 
Ovipositor 

of bee, 11. 

of cricket, 9. 

of grasshopper, 6. 
Pancreas 

of frog, 89. 

of pigeon, 111. 

of rabbit, 122. 
Paramoecium, 58. 
Peristome 

of sea-urchin, 162. 

of starfish, 154. 

of vorticella, 61. 
Peritoneum, 76, 121. 
Pigeon, 105. 
Porifera, 179. 
Protoplasm, 63. 
Protozoa, 63. 
Pseudopodium, 62. 
Rabbit, 119. 
Keflex action, 93. 
Reproductive organs 

of crayfish, 33. 

of earthworm, 42. 

of fish, 77. 

of frog, 89. 

of pigeon, 113. 

of sea-urchin, 164. 

of snake, 101. 

of starfish, 155. 

of turtle, 103. 
Respiration, 66, 67. 
Rotifer, 69. 
Sea-anemone, 171. 
Sea-fan, 174. 
Sea-feather, 174. 
Sea-urchin, 160. 
Segmentation, 119, 166. 
Skeleton 

of fish, 80, 81. 

of frog, 95. 

of pigeon, 115. 

of turtle, 104. 
Snail. 56. 
Snake, 98. 
Sow-bug, 36. 
Spermatozoa, 165. 
Spider, 21. 
Spinal curd 

of fish, 82. 

of flu. 

of pigeon. 11"). 
reflex action of, 93. 
of rabbit, 126, 

Spiracle, :;. 

Spleen 

of fish, 77. 

of fro 

of pig< , 112. 

of rabbit, 122. 

of snake, 101. 
Sponges, 176, 
Squash i>ult. 17. 
Starfish, 160. 



Stomach 

of crayfish, 33. 

of fish, 76. 

of frog, 89. 

of pigeon, 111, 112. 

of rabbit, 122. 

of snake, 100. 

of starfish, 155. 

of turtle, 103. 
Synovia, 135. 
Tendon, 113, 135. 
Testis 

of crayfish, 33. 

of fish, 78. 

of frog, 90. 

of pigeon, 113. 

of snake, 101. 
Teeth 

of clam-shell, 54. 

offish, 73,80. 

of rabbit, 120. 

of sea-urchin, 163. 

of snake, 99. 
Thorax, 1, 15, 131. 
Thousand legs, 22. 
Tissue, 66. 
Tongue 

of bee, 10. 

of fish, 73. 

of grasshopper, 2. 

of pigeon, 106. 

of snlike, 100. 
Trachea. See Windpipe. 
Trachea?, 5. 
Tube feet, 154, 163. 
Turtle, 102. 
Tympanum, •">, 87. 
Uterus, 118. 
Veins 

of fish. 70. 

of frog. 91. 

of grasshopper, 3. 

of pigeon, no. 

of rabbit, 12.">, 133. 

of sheep, 138. 

valves in, 142. 
Vermes, 45. 
Vertebra', SI. 
Villi, 124. 
Vocal cords, 149. 
Vorticella, 60. 
Water system 

of .sea-urchin, 164. 

of starfish, 159. 
Wheel animalcule, 69. 
Windpipe 

of pigeon, 106. 
of sheep, 136. 
of snake, 100. 
of turtle, 103. 
Wings 
of beetle, I s :. 
of butterfly, 12. 

of cricket. '.». 
of fly, I.',, If,. 

of pigeon, 106. 

Worm 



